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Instances and Images Guide

Red Hat OpenStack Platform 13

Managing Instances and Images

OpenStack Documentation Team

Abstract

The Instances and Images guide provides procedures for the management of instances, images of a Red Hat OpenStack Platform environment.

Preface

Red Hat OpenStack Platform (RHOSP) provides the foundation to build a private or public Infrastructure-as-a-Service (IaaS) cloud on top of Red Hat Enterprise Linux. It offers a scalable, fault-tolerant platform for the development of cloud-enabled workloads.

In RHOSP you can create, manage, and configure storage for images and instances.

You can manage the cloud by using either the OpenStack Dashboard or the command-line interface. You can use either method to perform most procedures, however some of the more advanced procedures can only be executed on the command line. This guide provides procedures for the Dashboard where possible.

Note

For the complete suite of documentation for Red Hat OpenStack Platform, see Red Hat OpenStack Platform Documentation Suite.

Chapter 1. Image service

You can manage images and storage in Red Hat OpenStack Platform (RHOSP).

A virtual machine image is a file that contains a virtual disk with a bootable operating system installed. Virtual machine images are supported in different formats. The following formats are available in RHOSP:

  • RAW - Unstructured disk image format.
  • QCOW2 - Disk format supported by QEMU emulator. This format includes QCOW2v3 (sometimes referred to as QCOW3), which requires QEMU 1.1 or higher.
  • ISO - Sector-by-sector copy of the data on a disk, stored in a binary file.
  • AKI - Indicates an Amazon Kernel Image.
  • AMI - Indicates an Amazon Machine Image.
  • ARI - Indicates an Amazon RAMDisk Image.
  • VDI - Disk format supported by VirtualBox virtual machine monitor and the QEMU emulator.
  • VHD - Common disk format used by virtual machine monitors from VMware, VirtualBox, and others.
  • VMDK - Disk format supported by many common virtual machine monitors.

Because ISO files contain bootable file systems with an installed operating system, you can use ISO files in the same way that you use other virtual machine image files.

To download the official Red Hat Enterprise Linux cloud images, your account must have a valid Red Hat Enterprise Linux subscription:

If you are not logged in to the Customer Portal, a prompt opens where you must enter your Red Hat account credentials.

1.1. Understanding and optimizing the Image service

You can use the following Red Hat OpenStack Platform (RHOSP) Image service (glance) features to manage and optimize images and storage in your RHOSP deployment.

1.1.1. Supported Image service (glance) back ends

The following Image service (glance) back end scenarios are supported:

  • RBD is the default back end when you use Ceph. For more information, see Configuring Ceph Storage in the Advanced Overcloud Customization guide.
  • Object Storage (swift). For more information, see Using an External Object Storage Cluster in the Advanced Overcloud Customization guide.
  • Block Storage (cinder). For more information, see Configuring cinder back end for the Image service in the Advanced Overcloud Customization guide.

    Note
    The Image service uses the Block Storage type and back end as the default.
  • NFS. For more information, see Configuring NFS Storage in the Advanced Overcloud Customization guide.

    Important

    Although NFS is a supported Image service deployment option, more robust options are available.

    NFS is not native to the Image service. When you mount an NFS share on the Image service, the Image service does not manage the operation. The Image service writes data to the file system but is unaware that the back end is an NFS share.

    In this type of deployment, the Image service cannot retry a request if the share fails. This means that when a failure occurs on the back end, the store might enter read-only mode, or it might continue to write data to the local file system, in which case you risk data loss. To recover from this situation, you must ensure that the share is mounted and in sync, and then restart the Image service. For these reasons, Red Hat does not recommend NFS as an Image service back end.

    However, if you do choose to use NFS as an Image service back end, some of the following best practices can help to mitigate risks:

    • Use a production-grade NFS back end.
    • Ensure that a Layer 2 connection is established between Controller nodes and the NFS back end.
    • Include monitoring and alerts for the mounted share.
    • Set underlying FS permissions.

      • Ensure that the user and the group that the glance-api process runs on do not have write permissions on the mount point at the local file system. This means that the process can detect possible mount failure and put the store into read-only mode during a write attempt.
      • The write permissions must be present in the shared file system that you use as a store.

1.1.2. Image signing and verification

Image signing and verification protects image integrity and authenticity by enabling deployers to sign images and save the signatures and public key certificates as image properties.

By taking advantage of this feature, you can:

  • Sign an image using your private key and upload the image, the signature, and a reference to your public key certificate (the verification metadata). The Image service then verifies that the signature is valid.
  • Create an image in the Compute service, have the Compute service sign the image, and upload the image and its verification metadata. The Image service again verifies that the signature is valid.
  • Request a signed image in the Compute service. The Image service provides the image and its verification metadata, allowing the Compute service to validate the image before booting it.

For information on image signing and verification, refer to the Validate Glance Images chapter of the Manage Secrets with OpenStack Key Manager Guide.

1.1.3. Image conversion

Image conversion converts images by calling the task API while importing an image.

As part of the import workflow, a plugin provides the image conversion. This plugin can be activated or deactivated based on the deployer configuration. Therefore, the deployer needs to specify the preferred format of images for the deployment.

Internally, the Image service receives the bits of the image in a particular format. These bits are stored in a temporary location. The plugin is then triggered to convert the image to the target format and moved to a final destination. When the task is finished, the temporary location is deleted. As a result, the format uploaded initially is not retained by the Image service.

For more information about image conversion, see Enabling image conversion.

Note

The conversion can be triggered only when importing an image. It does not run when uploading an image. For example:

$ glance image-create-via-import \
    --disk-format qcow2 \
    --container-format bare \
    --name NAME \
    --visibility public \
    --import-method web-download \
    --uri http://server/image.qcow2

1.1.4. Image introspection

Every image format comes with a set of metadata embedded inside the image itself. For example, a stream optimized vmdk would contain the following parameters:

$ head -20 so-disk.vmdk

# Disk DescriptorFile
version=1
CID=d5a0bce5
parentCID=ffffffff
createType="streamOptimized"

# Extent description
RDONLY 209714 SPARSE "generated-stream.vmdk"

# The Disk Data Base
#DDB

ddb.adapterType = "buslogic"
ddb.geometry.cylinders = "102"
ddb.geometry.heads = "64"
ddb.geometry.sectors = "32"
ddb.virtualHWVersion = "4"

By introspecting this vmdk, you can easily know that the disk_type is streamOptimized, and the adapter_type is buslogic. These metadata parameters are useful for the consumer of the image. In Compute, the workflow to instantiate a streamOptimized disk is different from the one to instantiate a flat disk. This new feature allows metadata extraction. You can achieve image introspection by calling the task API while importing the image. An administrator can override metadata settings.

1.1.5. Interoperable image import

The OpenStack Image service provides two methods for importing images using the interoperable image import workflow:

  • web-download (default) for importing images from a URI and
  • glance-direct for importing from a local file system.

1.2. Managing images

The OpenStack Image service (glance) provides discovery, registration, and delivery services for disk and server images. It provides the ability to copy or snapshot a server image, and immediately store it away. Stored images can be used as a template to get new servers up and running quickly and more consistently than installing a server operating system and individually configuring services.

1.2.1. Creating an image

This section provides you with the steps to manually create OpenStack-compatible images in the QCOW2 format using Red Hat Enterprise Linux 7 ISO files, Red Hat Enterprise Linux 6 ISO files, or Windows ISO files.

1.2.1.1. Using a KVM guest image with Red Hat OpenStack Platform

You can use a ready RHEL KVM guest QCOW2 image:

These images are configured with cloud-init and must take advantage of ec2-compatible metadata services for provisioning SSH keys in order to function properly.

Ready Windows KVM guest QCOW2 images are not available.

Note

For the KVM guest images:

  • The root account in the image is disabled, but sudo access is granted to a special user named cloud-user.
  • There is no root password set for this image.

The root password is locked in /etc/shadow by placing !! in the second field.

For an OpenStack instance, it is recommended that you generate an ssh keypair from the OpenStack dashboard or command line and use that key combination to perform an SSH public authentication to the instance as root.

When the instance is launched, this public key will be injected to it. You can then authenticate using the private key downloaded while creating the keypair.

If you do not want to use keypairs, you can use the admin password that has been set using the Inject an admin Password Into an Instance procedure.

If you want to create custom Red Hat Enterprise Linux or Windows images, see Create a Red Hat Enterprise Linux 7 Image, Create a Red Hat Enterprise Linux 6 Image, or Create a Windows Image.

1.2.1.2. Creating custom Red Hat Enterprise Linux or Windows images

Prerequisites:

  • Linux host machine to create an image. This can be any machine on which you can install and run the Linux packages.
  • libvirt, virt-manager (run command yum groupinstall -y @virtualization). This installs all packages necessary for creating a guest operating system.
  • Libguestfs tools (run command yum install -y libguestfs-tools-c). This installs a set of tools for accessing and modifying virtual machine images.
  • A Red Hat Enterprise Linux 7 or 6 ISO file (see RHEL 7.2 Binary DVD or RHEL 6.8 Binary DVD) or a Windows ISO file. If you do not have a Windows ISO file, visit the Microsoft TechNet Evaluation Center and download an evaluation image.
  • Text editor, if you want to change the kickstart files (RHEL only).
Note

In the following procedures, all commands with the [root@host]# prompt should be run on your host machine.

1.2.1.2.1. Creating a Red Hat Enterprise Linux 7 image

This section provides you with the steps to manually create an OpenStack-compatible image in the QCOW2 format using a Red Hat Enterprise Linux 7 ISO file.

  1. Start the installation using virt-install as shown below:

    [root@host]# qemu-img create -f qcow2 rhel7.qcow2 8G
    [root@host]# virt-install --virt-type kvm --name rhel7 --ram 2048 \
    --cdrom /tmp/rhel-server-7.2-x86_64-dvd.iso \
    --disk rhel7.qcow2,format=qcow2 \
    --network=bridge:virbr0 --graphics vnc,listen=0.0.0.0 \
    --noautoconsole --os-type=linux --os-variant=rhel7

    This launches an instance and starts the installation process.

    Note

    If the instance does not launch automatically, run the virt-viewer command to view the console:

    [root@host]# virt-viewer rhel7
  2. Set up the virtual machine as follows:

    1. At the initial Installer boot menu, choose the Install Red Hat Enterprise Linux 7.X option. RHEL7 Install1
    2. Choose the appropriate Language and Keyboard options.
    3. When prompted about which type of devices your installation uses, choose Auto-detected installation media. RHEL7 Install5
    4. When prompted about which type of installation destination, choose Local Standard Disks. RHEL7 Install6 For other storage options, choose Automatically configure partitioning.
    5. For software selection, choose Minimal Install.
    6. For network and host name, choose eth0 for network and choose a hostname for your device. The default host name is localhost.localdomain.
    7. Choose the root password. RHEL7 Install9 The installation process completes and the Complete! screen appears.
  3. After the installation is complete, reboot the instance and log in as the root user.
  4. Update the /etc/sysconfig/network-scripts/ifcfg-eth0 file so it only contains the following values:

    TYPE=Ethernet
    DEVICE=eth0
    ONBOOT=yes
    BOOTPROTO=dhcp
    NM_CONTROLLED=no
  5. Reboot the machine.
  6. Register the machine with the Content Delivery Network.

    # sudo subscription-manager register
    # sudo subscription-manager attach --pool=Valid-Pool-Number-123456
    # sudo subscription-manager repos --enable=rhel-7-server-rpms
  7. Update the system:

    # yum -y update
  8. Install the cloud-init packages:

    # yum install -y cloud-utils-growpart cloud-init
  9. Edit the /etc/cloud/cloud.cfg configuration file and under cloud_init_modules add:

    - resolv-conf

    The resolv-conf option automatically configures the resolv.conf when an instance boots for the first time. This file contains information related to the instance such as nameservers, domain and other options.

  10. Add the following line to /etc/sysconfig/network to avoid problems accessing the EC2 metadata service:

    NOZEROCONF=yes
  11. To ensure the console messages appear in the Log tab on the dashboard and the nova console-log output, add the following boot option to the /etc/default/grub file:

    GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=ttyS0,115200n8"

    Run the grub2-mkconfig command:

    # grub2-mkconfig -o /boot/grub2/grub.cfg

    The output is as follows:

    Generating grub configuration file ...
    Found linux image: /boot/vmlinuz-3.10.0-229.7.2.el7.x86_64
    Found initrd image: /boot/initramfs-3.10.0-229.7.2.el7.x86_64.img
    Found linux image: /boot/vmlinuz-3.10.0-121.el7.x86_64
    Found initrd image: /boot/initramfs-3.10.0-121.el7.x86_64.img
    Found linux image: /boot/vmlinuz-0-rescue-b82a3044fb384a3f9aeacf883474428b
    Found initrd image: /boot/initramfs-0-rescue-b82a3044fb384a3f9aeacf883474428b.img
    done
  12. Un-register the virtual machine so that the resulting image does not contain the same subscription details for every instance cloned based on it:

    # subscription-manager repos --disable=*
    # subscription-manager unregister
    # yum clean all
  13. Power off the instance:

    # poweroff
  14. Reset and clean the image using the virt-sysprep command so it can be used to create instances without issues:

    [root@host]# virt-sysprep -d rhel7
  15. Reduce image size using the virt-sparsify command. This command converts any free space within the disk image back to free space within the host:

    [root@host]# virt-sparsify --compress /tmp/rhel7.qcow2 rhel7-cloud.qcow2

    This creates a new rhel7-cloud.qcow2 file in the location from where the command is run.

The rhel7-cloud.qcow2 image file is ready to be uploaded to the Image service. For more information on uploading this image to your OpenStack deployment using the dashboard, see Upload an Image.

1.2.1.2.2. Creating a Red Hat Enterprise Linux 6 image

This section provides you with the steps to manually create an OpenStack-compatible image in the QCOW2 format using a Red Hat Enterprise Linux 6 ISO file.

  1. Start the installation using virt-install:

    [root@host]# qemu-img create -f qcow2 rhel6.qcow2 4G
    [root@host]# virt-install --connect=qemu:///system --network=bridge:virbr0 \
    --name=rhel6 --os-type linux --os-variant rhel6 \
    --disk path=rhel6.qcow2,format=qcow2,size=10,cache=none \
    --ram 4096 --vcpus=2 --check-cpu --accelerate \
    --hvm --cdrom=rhel-server-6.8-x86_64-dvd.iso

    This launches an instance and starts the installation process.

    Note

    If the instance does not launch automatically, run the virt-viewer command to view the console:

    [root@host]# virt-viewer rhel6
  2. Set up the virtual machines as follows:

    1. At the initial Installer boot menu, choose the Install or upgrade an existing system option. RHEL6 Install1 Step through the installation prompts. Accept the defaults.

      The installer checks for the disc and lets you decide whether you want to test your installation media before installation. Select OK to run the test or Skip to proceed without testing.

    2. Choose the appropriate Language and Keyboard options.
    3. When prompted about which type of devices your installation uses, choose Basic Storage Devices. RHEL6 Install3
    4. Choose a hostname for your device. The default host name is localhost.localdomain.
    5. Set timezone and root password.
    6. Based on the space on the disk, choose the type of installation. RHEL6 Install4
    7. Choose the Basic Server install, which installs an SSH server. RHEL6 Install5
    8. The installation process completes and Congratulations, your Red Hat Enterprise Linux installation is complete screen appears.
  3. Reboot the instance and log in as the root user.
  4. Update the /etc/sysconfig/network-scripts/ifcfg-eth0 file so it only contains the following values:

    TYPE=Ethernet
    DEVICE=eth0
    ONBOOT=yes
    BOOTPROTO=dhcp
    NM_CONTROLLED=no
  5. Reboot the machine.
  6. Register the machine with the Content Delivery Network:

    # sudo subscription-manager register
    # sudo subscription-manager attach --pool=Valid-Pool-Number-123456
    # sudo subscription-manager repos --enable=rhel-6-server-rpms
  7. Update the system:

    # yum -y update
  8. Install the cloud-init packages:

    # yum install -y cloud-utils-growpart cloud-init
  9. Edit the /etc/cloud/cloud.cfg configuration file and under cloud_init_modules add:

    - resolv-conf

    The resolv-conf option automatically configures the resolv.conf configuration file when an instance boots for the first time. This file contains information related to the instance such as nameservers, domain, and other options.

  10. To prevent network issues, create the /etc/udev/rules.d/75-persistent-net-generator.rules file as follows:

    # echo "#" > /etc/udev/rules.d/75-persistent-net-generator.rules

    This prevents /etc/udev/rules.d/70-persistent-net.rules file from being created. If /etc/udev/rules.d/70-persistent-net.rules is created, networking may not function properly when booting from snapshots (the network interface is created as "eth1" rather than "eth0" and IP address is not assigned).

  11. Add the following line to /etc/sysconfig/network to avoid problems accessing the EC2 metadata service:

    NOZEROCONF=yes
  12. To ensure the console messages appear in the Log tab on the dashboard and the nova console-log output, add the following boot option to the /etc/grub.conf:

    console=tty0 console=ttyS0,115200n8
  13. Un-register the virtual machine so that the resulting image does not contain the same subscription details for every instance cloned based on it:

    # subscription-manager repos --disable=*
    # subscription-manager unregister
    # yum clean all
  14. Power off the instance:

    # poweroff
  15. Reset and clean the image using the virt-sysprep command so it can be used to create instances without issues:

    [root@host]# virt-sysprep -d rhel6
  16. Reduce image size using the virt-sparsify command. This command converts any free space within the disk image back to free space within the host:

    [root@host]# virt-sparsify --compress rhel6.qcow2 rhel6-cloud.qcow2

    This creates a new rhel6-cloud.qcow2 file in the location from where the command is run.

    Note

    You will need to manually resize the partitions of instances based on the image in accordance with the disk space in the flavor that is applied to the instance.

The rhel6-cloud.qcow2 image file is ready to be uploaded to the Image service. For more information on uploading this image to your OpenStack deployment using the dashboard, see Upload an Image

1.2.1.2.3. Creating a Windows image

This section provides you with the steps to manually create an OpenStack-compatible image in the QCOW2 format using a Windows ISO file.

  1. Start the installation using virt-install as shown below:

    [root@host]# virt-install --name=name \
    --disk size=size \
    --cdrom=path \
    --os-type=windows \
    --network=bridge:virbr0 \
    --graphics spice \
    --ram=RAM

    Replace the values of the virt-install parameters as follows:

    • name — the name that the Windows guest should have.
    • size — disk size in GB.
    • path — the path to the Windows installation ISO file.
    • RAM — the requested amount of RAM in MB.

      Note

      The --os-type=windows parameter ensures that the clock is set up correctly for the Windows guest, and enables its Hyper-V enlightenment features.

      Note that virt-install saves the guest image as /var/lib/libvirt/images/name.qcow2 by default. If you want to keep the guest image elsewhere, change the parameter of the --disk option as follows:

      --disk path=filename,size=size

      Replace filename with the name of the file which should store the guest image (and optionally its path); for example path=win8.qcow2,size=8 creates an 8 GB file named win8.qcow2 in the current working directory.

      Tip

      If the guest does not launch automatically, run the virt-viewer command to view the console:

      [root@host]# virt-viewer name
  2. Installation of Windows systems is beyond the scope of this document. For instructions on how to install Windows, see the relevant Microsoft documentation.
  3. To allow the newly installed Windows system to use the virtualized hardware, you may need to install virtio drivers in it. To so do, first install the virtio-win package on the host system. This package contains the virtio ISO image, which is to be attached as a CD-ROM drive to the Windows guest. See Chapter 8. KVM Para-virtualized (virtio) Drivers in the Virtualization Deployment and Administration Guide for detailed instructions on how to install the virtio-win package, add the virtio ISO image to the guest, and install the virtio drivers.
  4. To complete the setup, download and execute Cloudbase-Init on the Windows system. At the end of the installation of Cloudbase-Init, select the Run Sysprep and Shutdown check boxes. The Sysprep tool makes the guest unique by generating an OS ID, which is used by certain Microsoft services.

    Important

    Red Hat does not provide technical support for Cloudbase-Init. If you encounter an issue, contact Cloudbase Solutions.

When the Windows system shuts down, the name.qcow2 image file is ready to be uploaded to the Image service. For more information on uploading this image to your OpenStack deployment using the dashboard or the command line, see Upload an Image.

1.2.1.3. Using libosinfo

Image Service (glance) can process libosinfo data for images, making it easier to configure the optimal virtual hardware for an instance. This can be done by adding the libosinfo-formatted operating system name to the glance image.

  1. This example specifies that the image with ID 654dbfd5-5c01-411f-8599-a27bd344d79b uses the libosinfo value of rhel7.2:

    $ openstack image set 654dbfd5-5c01-411f-8599-a27bd344d79b --property os_name=rhel7.2

    As a result, Compute will supply virtual hardware optimized for rhel7.2 whenever an instance is built using the 654dbfd5-5c01-411f-8599-a27bd344d79b image.

    Note

    For a complete list of libosinfo values, refer to the libosinfo project: https://gitlab.com/libosinfo/osinfo-db/tree/master/data/os

1.2.2. Uploading an image

  1. In the dashboard, select Project > Compute > Images.
  2. Click Create Image.
  3. Fill out the values, and click Create Image when finished.

Table 1.1. Image Options

FieldNotes

Name

Name for the image. The name must be unique within the project.

Description

Brief description to identify the image.

Image Source

Image source: Image Location or Image File. Based on your selection, the next field is displayed.

Image Location or Image File

  • Select Image Location option to specify the image location URL.
  • Select Image File option to upload an image from the local disk.

Format

Image format (for example, qcow2).

Architecture

Image architecture. For example, use i686 for a 32-bit architecture or x86_64 for a 64-bit architecture.

Minimum Disk (GB)

Minimum disk size required to boot the image. If this field is not specified, the default value is 0 (no minimum).

Minimum RAM (MB)

Minimum memory size required to boot the image. If this field is not specified, the default value is 0 (no minimum).

Public

If selected, makes the image public to all users with access to the project.

Protected

If selected, ensures only users with specific permissions can delete this image.

When the image has been successfully uploaded, its status is changed to active, which indicates that the image is available for use. Note that the Image service can handle even large images that take a long time to upload — longer than the lifetime of the Identity service token which was used when the upload was initiated. This is due to the fact that the Image service first creates a trust with the Identity service so that a new token can be obtained and used when the upload is complete and the status of the image is to be updated.

Note

You can also use the glance image-create command with the property option to upload an image. More values are available on the command line. For a complete listing, see Image Configuration Parameters.

1.2.3. Updating an image

  1. In the dashboard, select Project > Compute > Images.
  2. Click Edit Image from the dropdown list.

    Note

    The Edit Image option is available only when you log in as an admin user. When you log in as a demo user, you have the option to Launch an instance or Create Volume.

  3. Update the fields and click Update Image when finished. You can update the following values - name, description, kernel ID, ramdisk ID, architecture, format, minimum disk, minimum RAM, public, protected.
  4. Click the drop-down menu and select Update Metadata option.
  5. Specify metadata by adding items from the left column to the right one. In the left column, there are metadata definitions from the Image Service Metadata Catalog. Select Other to add metadata with the key of your choice and click Save when finished.
Note

You can also use the glance image-update command with the property option to update an image. More values are available on the command line; for a complete listing, see Image Configuration Parameters.

1.2.4. Importing an image

You can import images into the Image service (glance) using web-download to import an image from a URI and glance-direct to import an image from a local file system. The web-download option is enabled by default.

Import methods are configured by the cloud administrator. Run the glance import-info command to list available import options.

1.2.4.1. Importing from a remote URI

You can use the web-download method to copy an image from a remote URI using a two-stage process. First, an image record is created and then the image is retrieved from a URI. This method provides a more secure way to import images than the deprecated copy-from method used in Image API v1.

  1. Create an image and specify the URI of the image to import.

    glance image-create --uri <URI>
  2. You can monitor the image’s availability using the glance image-show <image-ID> command where the ID is the one provided during image creation.

1.2.4.2. Importing from a local volume

The glance-direct method creates an image record, which generates an image ID. Once the image is uploaded to the service from a local volume, it is stored in a staging area and is made active after it passes any configured checks. The glance-direct method requires a shared staging area when used in a highly available (HA) configuration.

Note

Image uploads using the glance-direct method fail in an HA environment if a common staging area is not present. In an HA active-active environment, API calls are distributed to the glance controllers. The download API call could be sent to a different controller than the API call to upload the image. For more information about configuring the staging area, refer to the Storage Configuration section in the Advanced Overcloud Customization Guide.

The glance-direct method uses three different calls to import an image:

  • glance image-create
  • glance image-stage
  • glance image-import

You can use the glance image-create-via-import command to perform all three of these calls in one command. In the example below, uppercase words should be replaced with the appropriate options.

glance image-create-via-import --container-format FORMAT --disk-format DISKFORMAT --name NAME --file /PATH/TO/IMAGE

Once the image moves from the staging area to the back end location, the image is listed. However, it may take some time for the image to become active.

You can monitor the image’s availability using the glance image-show <image-ID> command where the ID is the one provided during image creation.

1.2.5. Deleting an image

  1. In the dashboard, select Project > Compute > Images.
  2. Select the image you want to delete and click Delete Images.

1.2.6. Enabling image conversion

With the GlanceImageImportPlugins parameter enabled, you can upload a QCOW2 image, and the Image service will convert it to RAW.

To enable image conversion, create an environment file that contains the following parameter value and include the new environment file with the -e option in the openstack overcloud deploy command:

parameter_defaults:
  GlanceImageImportPlugins:'image_conversion'

1.2.7. Converting an image to RAW format

Red Hat Ceph can store, but does not support using, QCOW2 images to host virtual machine (VM) disks.

When you upload a QCOW2 image and create a VM from it, the compute node downloads the image, converts the image to RAW, and uploads it back into Ceph, which can then use it. This process affects the time it takes to create VMs, especially during parallel VM creation.

For example, when you create multiple VMs simultaneously, uploading the converted image to the Ceph cluster may impact already running workloads. The upload process can starve those workloads of IOPS and impede storage responsiveness.

To boot VMs in Ceph more efficiently (ephemeral back end or boot from volume), the glance image format must be RAW.

Converting an image to RAW may yield an image that is larger in size than the original QCOW2 image file. Run the following command before the conversion to determine the final RAW image size:

qemu-img info <image>.qcow2

To convert an image from QCOW2 to RAW format, do the following:

qemu-img convert -p -f qcow2 -O raw <original qcow2 image>.qcow2 <new raw image>.raw

1.2.7.1. Configuring Image Service to accept RAW and ISO only

Optionally, to configure the Image Service to accept only RAW and ISO image formats, deploy using an additional environment file that contains the following:

parameter_defaults:
  ExtraConfig:
    glance::config::api_config:
      image_format/disk_formats:
        value: "raw,iso"

1.2.8. Storing an image in RAW format

With the GlanceImageImportPlugins parameter enabled, run the following command to upload a QCOW2 image and automatically convert it to RAW format.

$ glance image-create-via-import \
    --disk-format qcow2 \
    --container-format bare \
    --name NAME \
    --visibility public \
    --import-method web-download \
    --uri http://server/image.qcow2
  • For --name, replace NAME with the name of the image; this is the name that will appear in glance image-list.
  • For --uri, replace http://server/image.qcow2 with the location and file name of the QCOW2 image.
Note

This command example creates the image record and imports it by using the web-download method. The glance-api downloads the image from the --uri location during the import process. If web-download is not available, glanceclient cannot automatically download the image data. Run the glance import-info command to list the available image import methods.

Chapter 2. Configuring the Compute (nova) service

Use environment files to customize the Compute (nova) service. Puppet generates and stores this configuration in the /var/lib/config-data/puppet-generated/<nova_container>/etc/nova/nova.conf file. Use the following configuration methods to customize the Compute service configuration:

  • Heat parameters - as detailed in the Compute (nova) Parameters section in the Overcloud Parameters guide. For example:

    parameter_defaults:
      NovaSchedulerDefaultFilters: AggregateInstanceExtraSpecsFilter,RetryFilter,ComputeFilter,ComputeCapabilitiesFilter,ImagePropertiesFilter
      NovaNfsEnabled: true
      NovaNfsShare: '192.0.2.254:/export/nova'
      NovaNfsOptions: 'context=system_u:object_r:nfs_t:s0'
      NovaNfsVersion: '4.2'
  • Puppet parameters - as defined in /etc/puppet/modules/nova/manifests/*:

    parameter_defaults:
        ComputeExtraConfig:
            nova::compute::force_raw_images: True
    Note

    Only use this method if an equivalent heat parameter does not exist.

  • Manual hieradata overrides - for customizing parameters when no heat or Puppet parameter exists. For example, the following sets the disk_allocation_ratio in the [DEFAULT] section on the Compute role:

    parameter_defaults:
        ComputeExtraConfig:
            nova::config::nova_config:
                DEFAULT/disk_allocation_ratio:
                    value: '2.0'
Warning

If a heat parameter exists, it must be used instead of the Puppet parameter; if a Puppet parameter exists, but not a heat parameter, then the Puppet parameter must be used instead of the manual override method. The manual override method must only be used if there is no equivalent heat or Puppet parameter.

Tip

Follow the guidance in Identifying Parameters to Modify to determine if a heat or Puppet parameter is available for customizing a particular configuration.

See Parameters in the Advanced Overcloud Customization guide for further details on configuring overcloud services.

2.1. Configuring memory for overallocation

When you use memory overcommit (NovaRAMAllocationRatio >= 1.0), you need to deploy your overcloud with enough swap space to support the allocation ratio.

Note

If your NovaRAMAllocationRatio parameter is set to < 1, follow the RHEL recommendations for swap size. For more information, see Recommended system swap space in the RHEL Managing Storage Devices guide.

Prerequisites

Procedure

  1. Copy the /usr/share/openstack-tripleo-heat-templates/environments/enable-swap.yaml file to your environment file directory:

    $ cp /usr/share/openstack-tripleo-heat-templates/environments/enable-swap.yaml /home/stack/templates/enable-swap.yaml
  2. Configure the swap size by adding the following parameters to your enable-swap.yaml file:

    parameter_defaults:
      swap_size_megabytes: <swap size in MB>
      swap_path: <full path to location of swap, default: /swap>
  3. To apply this configuration, add the enable_swap.yaml environment file to the stack with your other environment files and deploy the overcloud:

    (undercloud) $ openstack overcloud deploy --templates \
      -e [your environment files] \
      -e /home/stack/templates/enable-swap.yaml \

2.2. Calculating reserved host memory on Compute nodes

To determine the total amount of RAM to reserve for host processes, you need to allocate enough memory for each of the following:

  • The resources that run on the node, for instance, OSD consumes 3 GB of memory.
  • The emulator overhead required to visualize instances on a host.
  • The hypervisor for each instance.

After you calculate the additional demands on memory, use the following formula to help you determine the amount of memory to reserve for host processes on each node:

NovaReservedHostMemory = total_RAM - ( (vm_no * (avg_instance_size + overhead)) + (resource1 * resource_ram) + (resource _n_ * resource_ram))
  • Replace vm_no with the number of instances.
  • Replace avg_instance_size with the average amount of memory each instance can use.
  • Replace overhead with the hypervisor overhead required for each instance.
  • Replace resource1 with the number of a resource type on the node.
  • Replace resource_ram with the amount of RAM each resource of this type requires.

2.3. Calculating swap size

The allocated swap size must be large enough to handle any memory overcommit. You can use the following formulas to calculate the swap size your node requires:

  • overcommit_ratio = NovaRAMAllocationRatio - 1
  • Minimum swap size (MB) = (total_RAM * overcommit_ratio) + RHEL_min_swap
  • Recommended (maximum) swap size (MB) = total_RAM * (overcommit_ratio + percentage_of_RAM_to_use_for_swap)

The percentage_of_RAM_to_use_for_swap variable creates a buffer to account for QEMU overhead and any other resources consumed by the operating system or host services.

For instance, to use 25% of the available RAM for swap, with 64GB total RAM, and NovaRAMAllocationRatio set to 1:

  • Recommended (maximum) swap size = 64000 MB * (0 + 0.25) = 16000 MB

For information on how to calculate the NovaReservedHostMemory value, see Section 2.2, “Calculating reserved host memory on Compute nodes”.

For information on how to determine the RHEL_min_swap value, see Recommended system swap space in the RHEL Managing Storage Devices guide.

Chapter 3. Configuring OpenStack Compute storage

This chapter describes the architecture for the back-end storage of images in OpenStack Compute (nova), and provides basic configuration options.

3.1. Architecture overview

In Red Hat OpenStack Platform, the OpenStack Compute service uses the KVM hypervisor to execute compute workloads. The libvirt driver handles all interactions with KVM, and enables the creation of virtual machines.

Two types of libvirt storage must be considered for Compute:

  • Base image, which is a cached and formatted copy of the Image service image.
  • Instance disk, which is created using the libvirt base and is the back end for the virtual machine instance. Instance disk data can be stored either in Compute’s ephemeral storage (using the libvirt base) or in persistent storage (for example, using Block Storage).

Creation of Virtual Machines

The steps that Compute takes to create a virtual machine instance are:

  1. Cache the Image service’s backing image as the libvirt base.
  2. Convert the base image to the raw format (if configured).
  3. Resize the base image to match the VM’s flavor specifications.
  4. Use the base image to create the libvirt instance disk.

In the diagram above, the #1 instance disk uses ephemeral storage; the #2 disk uses a block-storage volume.

Ephemeral storage is an empty, unformatted, additional disk available to an instance. This storage value is defined by the instance flavor. The value provided by the user must be less than or equal to the ephemeral value defined for the flavor. The default value is 0, meaning no ephemeral storage is created.

The ephemeral disk appears in the same way as a plugged-in hard drive or thumb drive. It is available as a block device which you can check using the lsblk command. You can format it, mount it, and use it however you normally would a block device. There is no way to preserve or reference that disk beyond the instance it is attached to.

Block storage volume is persistant storage available to an instance regardless of the state of the running instance.

3.2. Configuration

You can configure performance tuning and security for your virtual disks by customizing the Compute (nova) configuration files. Compute is configured in custom environment files and Heat templates using the parameters detailed in the Compute (nova) Parameters section in the Overcloud Parameters guide. This configuration is generated and stored in the /var/lib/config-data/puppet-generated/<nova_container>/etc/nova/nova.conf file, as detailed in the following table.

Table 3.1. Compute Image Parameters

SectionParameterDescriptionDefault

[DEFAULT]

force_raw_images

Whether to convert a non-raw cached base image to be raw (boolean). If a non-raw image is converted to raw, Compute:

  • Disallows backing files (which might be a security issue).
  • Removes existing compression (to avoid CPU bottlenecks).

Converting the base to raw uses more space for any image that could have been used directly by the hypervisor (for example, a qcow2 image). If you have a system with slower I/O or less available space, you might want to specify false, trading the higher CPU requirements of compression for that of minimized input bandwidth.

Raw base images are always used with libvirt_images_type=lvm.

true

[DEFAULT]

use_cow_images

Whether to use CoW (Copy on Write) images for libvirt instance disks (boolean):

  • false - The raw format is used. Without CoW, more space is used for common parts of the disk image
  • true - The cqow2 format is used. With CoW, depending on the backing store and host caching, there may be better concurrency achieved by having each VM operate on its own copy.

true

[DEFAULT]

preallocate_images

Preallocation mode for libvirt instance disks. Value can be:

  • none - No storage is provisioned at instance start.
  • space - Storage is fully allocated at instance start (using fallocate), which can help with both space guarantees and I/O performance.

Even when not using CoW instance disks, the copy each VM gets is sparse and so the VM may fail unexpectedly at run time with ENOSPC. By running fallocate(1) on the instance disk images, Compute immediately and efficiently allocates the space for them in the file system (if supported). Run time performance should also be improved because the file system does not have to dynamically allocate blocks at run time (reducing CPU overhead and more importantly file fragmentation).

none

[DEFAULT]

resize_fs_using_block_device

Whether to enable direct resizing of the base image by accessing the image over a block device (boolean). This is only necessary for images with older versions of cloud-init (that cannot resize themselves).

Because this parameter enables the direct mounting of images which might otherwise be disabled for security reasons, it is not enabled by default.

false

[DEFAULT]

default_ephemeral_format

The default format that is used for a new ephemeral volume. Value can be: ext2, ext3, or ext4. The ext4 format provides much faster initialization times than ext3 for new, large disks. You can also override per instance using the guest_format configuration option.

ext4

[DEFAULT]

image_cache_manager_interval

Number of seconds to wait between runs of the image cache manager, which impacts base caching on libvirt compute nodes. This period is used in the auto removal of unused cached images (see remove_unused_base_images and remove_unused_original_minimum_age_seconds).

2400

[DEFAULT]

remove_unused_base_images

Whether to enable the automatic removal of unused base images (checked every image_cache_manager_interval seconds). Images are defined as unused if they have not been accessed in remove_unused_original_minimum_age_seconds seconds.

true

[DEFAULT]

remove_unused_original_minimum_age_seconds

How old an unused base image must be before being removed from the libvirt cache (see remove_unused_base_images).

86400

[libvirt]

images_type

Image type to use for libvirt instance disks (deprecates use_cow_images). Value can be: raw, qcow2, lvm, rbd, or default. If default is specified, the value used for the use_cow_images parameter is used.

default

Chapter 4. Virtual machine instances

OpenStack Compute is the central component that provides virtual machines on demand. Compute interacts with the Identity service for authentication, Image service for images (used to launch instances), and the dashboard service for the user and administrative interface.

Red Hat OpenStack Platform allows you to easily manage virtual machine instances in the cloud. The Compute service creates, schedules, and manages instances, and exposes this functionality to other OpenStack components. This chapter discusses these procedures along with procedures to add components like key pairs, security groups, host aggregates and flavors. The term instance is used by OpenStack to mean a virtual machine instance.

4.1. Managing instances

Before you can create an instance, you need to ensure certain other OpenStack components (for example, a network, key pair and an image or a volume as the boot source) are available for the instance.

This section discusses the procedures to add these components, create and manage an instance. Managing an instance refers to updating, and logging in to an instance, viewing how the instances are being used, resizing or deleting them.

4.1.1. Adding components

Use the following sections to create a network, key pair and upload an image or volume source. These components are used in the creation of an instance and are not available by default. You will also need to create a new security group to allow SSH access to the user.

  1. In the dashboard, select Project.
  2. Select Network > Networks, and ensure there is a private network to which you can attach the new instance (to create a network, see Create a Network section in the Networking Guide).
  3. Select Compute > Access & Security > Key Pairs, and ensure there is a key pair (to create a key pair, see Section 4.2.1.1, “Creating a key pair”).
  4. Ensure that you have either an image or a volume that can be used as a boot source:

  5. Select Compute > Access & Security > Security Groups, and ensure you have created a security group rule (to create a security group, see Project Security Management in the Users and Identity Management Guide).

4.1.2. Launching an instance

Launch one or more instances from the dashboard.

Note

Instances are launched by default using the Launch Instance form. However, you can also enable a Launch Instance wizard that simplifies the steps required. For more information, see Appendix B, Enabling the launch instance wizard.

  1. In the dashboard, select Project > Compute > Instances.
  2. Click Launch Instance.
  3. Fill out the fields ('* ' indicates a required field), and click Launch.

One or more instances are created, and launched based on the options provided.

Caution

It is not possible to launch an instance with a Block Storage (cinder) volume if the root disk size is larger than the HDD of the Compute node. Use one of the following workarounds to allow an instance to be launched with a Block Storage volume:

  • Use a flavor with the root disk and ephemeral disk set to “0”.
  • Remove DiskFilter from the NovaSchedulerDefaultFilters configuration.

4.1.2.1. Launching instance options

The following table outlines the options available when launching a new instance using the Launch Instance form. The same options are also available in the Launch instance wizard.

Table 4.1. Launch Instance Form Options

TabFieldNotes

Project and User

Project

Select the project from the dropdown list.

 

User

Select the user from the dropdown list.

Details

Availability Zone

Zones are logical groupings of cloud resources in which your instance can be placed. If you are unsure, use the default zone (for more information, see Section 4.4, “Managing host aggregates”).

 

Instance Name

A name to identify your instance.

 

Flavor

The flavor determines what resources the instance is given (for example, memory). For default flavor allocations and information on creating new flavors, see Section 4.3, “Managing flavors”.

 

Instance Count

The number of instances to create with these parameters. "1" is preselected.

 

Instance Boot Source

Depending on the item selected, new fields are displayed allowing you to select the source:

Access and Security

Key Pair

The specified key pair is injected into the instance and is used to remotely access the instance using SSH (if neither a direct login information or a static key pair is provided). Usually one key pair per project is created.

 

Security Groups

Security groups contain firewall rules which filter the type and direction of the instance’s network traffic (for more information on configuring groups, see Project Security Management in the Users and Identity Management Guide).

Networking

Selected Networks

You must select at least one network. Instances are typically assigned to a private network, and then later given a floating IP address to enable external access.

Post-Creation

Customization Script Source

You can provide either a set of commands or a script file, which will run after the instance is booted (for example, to set the instance host name or a user password). If Direct Input is selected, write your commands in the Script Data field; otherwise, specify your script file.

Note

Any script that starts with #cloud-config is interpreted as using the cloud-config syntax (for information on the syntax, see http://cloudinit.readthedocs.org/en/latest/topics/examples.html).

Advanced Options

Disk Partition

By default, the instance is built as a single partition and dynamically resized as needed. However, you can choose to manually configure the partitions yourself.

 

Configuration Drive

If selected, OpenStack writes metadata to a read-only configuration drive that is attached to the instance when it boots (instead of to Compute’s metadata service). After the instance has booted, you can mount this drive to view its contents (enables you to provide files to the instance).

4.1.3. Updating an instance

You can update an instance by selecting Project > Compute > Instances, and selecting an action for that instance in the Actions column. Actions allow you to manipulate the instance in a number of ways:

Table 4.2. Update Instance Options

ActionDescription

Create Snapshot

Snapshots preserve the disk state of a running instance. You can create a snapshot to migrate the instance, as well as to preserve backup copies.

Associate/Disassociate Floating IP

You must associate an instance with a floating IP (external) address before it can communicate with external networks, or be reached by external users. Because there are a limited number of external addresses in your external subnets, it is recommended that you disassociate any unused addresses.

Edit Instance

Update the instance’s name and associated security groups.

Edit Security Groups

Add and remove security groups to or from this instance using the list of available security groups (for more information on configuring groups, see Project Security Management in the Users and Identity Management Guide).

Console

View the instance’s console in the browser (allows easy access to the instance).

View Log

View the most recent section of the instance’s console log. Once opened, you can view the full log by clicking View Full Log.

Pause/Resume Instance

Immediately pause the instance (you are not asked for confirmation); the state of the instance is stored in memory (RAM).

Suspend/Resume Instance

Immediately suspend the instance (you are not asked for confirmation); like hibernation, the state of the instance is kept on disk.

Resize Instance

Bring up the Resize Instance window (see Section 4.1.4, “Resizing an instance”).

Soft Reboot

Gracefully stop and restart the instance. A soft reboot attempts to gracefully shut down all processes before restarting the instance.

Hard Reboot

Stop and restart the instance. A hard reboot effectively just shuts down the instance’s power and then turns it back on.

Shut Off Instance

Gracefully stop the instance.

Rebuild Instance

Use new image and disk-partition options to rebuild the image (shut down, re-image, and re-boot the instance). If encountering operating system issues, this option is easier to try than terminating the instance and starting over.

Terminate Instance

Permanently destroy the instance (you are asked for confirmation).

You can create and allocate an external IP address, see Section 4.2.3, “Creating, assigning, and releasing floating IP addresses”

4.1.4. Resizing an instance

To resize an instance (memory or CPU count), you must select a new flavor for the instance that has the right capacity. If you are increasing the size, remember to first ensure that the host has enough space.

  1. Ensure communication between hosts by setting up each host with SSH key authentication so that Compute can use SSH to move disks to other hosts (for example, compute nodes can share the same SSH key).
  2. Enable resizing on the original host by setting the allow_resize_to_same_host parameter to "True" in your Compute environment file.

    Note

    The allow_resize_to_same_host parameter does not resize the instance on the same host. Even if the parameter equals "True" on all Compute nodes, the scheduler does not force the instance to resize on the same host. This is the expected behavior.

  3. In the dashboard, select Project > Compute > Instances.
  4. Click the instance’s Actions arrow, and select Resize Instance.
  5. Select a new flavor in the New Flavor field.
  6. If you want to manually partition the instance when it launches (results in a faster build time):

    1. Select Advanced Options.
    2. In the Disk Partition field, select Manual.
  7. Click Resize.

4.1.5. Connecting to an instance

This section discusses the different methods you can use to access an instance console using the dashboard or the command-line interface. You can also directly connect to an instance’s serial port allowing you to debug even if the network connection fails.

4.1.5.1. Accessing an instance console using the dashboard

The console allows you a way to directly access your instance within the dashboard.

  1. In the dashboard, select Compute > Instances.
  2. Click the instance’s More button and select Console. console access
  3. Log in using the image’s user name and password (for example, a CirrOS image uses cirros/cubswin:)).

4.1.5.2. Connecting directly to a VNC console

You can directly access an instance’s VNC console using a URL returned by nova get-vnc-console command.

Browser

To obtain a browser URL, use:

$ nova get-vnc-console INSTANCE_ID novnc
Java Client

To obtain a Java-client URL, use:

$ nova get-vnc-console INSTANCE_ID xvpvnc
Note

nova-xvpvncviewer provides a simple example of a Java client. To download the client, use:

# git clone https://github.com/cloudbuilders/nova-xvpvncviewer
# cd nova-xvpvncviewer/viewer
# make

Run the viewer with the instance’s Java-client URL:

# java -jar VncViewer.jar URL

This tool is provided only for customer convenience, and is not officially supported by Red Hat.

4.1.6. Viewing instance usage

The following usage statistics are available:

  • Per Project

    To view instance usage per project, select Project > Compute > Overview. A usage summary is immediately displayed for all project instances.

    You can also view statistics for a specific period of time by specifying the date range and clicking Submit.

  • Per Hypervisor

    If logged in as an administrator, you can also view information for all projects. Click Admin > System and select one of the tabs. For example, the Resource Usage tab offers a way to view reports for a distinct time period. You might also click Hypervisors to view your current vCPU, memory, or disk statistics.

    Note

    The vCPU Usage value (x of y) reflects the number of total vCPUs of all virtual machines (x) and the total number of hypervisor cores (y).

4.1.7. Deleting an instance

  1. In the dashboard, select Project > Compute > Instances, and select your instance.
  2. Click Terminate Instance.
Note

Deleting an instance does not delete its attached volumes; you must do this separately (see Delete a Volume in the Storage Guide).

4.1.8. Managing multiple instances simultaneously

If you need to start multiple instances at the same time (for example, those that were down for compute or controller maintenance) you can do so easily at Project > Compute > Instances:

  1. Click the check boxes in the first column for the instances that you want to start. If you want to select all of the instances, click the check box in the first row in the table.
  2. Click More Actions above the table and select Start Instances.

Similarly, you can shut off or soft reboot multiple instances by selecting the respective actions.

4.2. Managing instance security

You can manage access to an instance by assigning it the correct security group (set of firewall rules) and key pair (enables SSH user access). Further, you can assign a floating IP address to an instance to enable external network access. The sections below outline how to create and manage key pairs, security groups, floating IP addresses and logging in to an instance using SSH. There is also a procedure for injecting an admin password in to an instance.

For information on managing security groups, see Project Security Management in the Users and Identity Management Guide.

4.2.1. Managing key pairs

Key pairs provide SSH access to the instances. Each time a key pair is generated, its certificate is downloaded to the local machine and can be distributed to users. Typically, one key pair is created for each project (and used for multiple instances).

You can also import an existing key pair into OpenStack.

4.2.1.1. Creating a key pair

  1. In the dashboard, select Project > Compute > Access & Security.
  2. On the Key Pairs tab, click Create Key Pair.
  3. Specify a name in the Key Pair Name field, and click Create Key Pair.

When the key pair is created, a key pair file is automatically downloaded through the browser. Save this file for later connections from external machines. For command-line SSH connections, you can load this file into SSH by executing:

# ssh-add ~/.ssh/os-key.pem

4.2.1.2. Importing a key pair

  1. In the dashboard, select Project > Compute > Access & Security.
  2. On the Key Pairs tab, click Import Key Pair.
  3. Specify a name in the Key Pair Name field, and copy and paste the contents of your public key into the Public Key field.
  4. Click Import Key Pair.

4.2.1.3. Deleting a key pair

  1. In the dashboard, select Project > Compute > Access & Security.
  2. On the Key Pairs tab, click the key’s Delete Key Pair button.

4.2.2. Creating a security group

Security groups are sets of IP filter rules that can be assigned to project instances, and which define networking access to the instance. Security group are project specific; project members can edit the default rules for their security group and add new rule sets.

  1. In the dashboard, select the Project tab, and click Compute > Access & Security.
  2. On the Security Groups tab, click + Create Security Group.
  3. Provide a name and description for the group, and click Create Security Group.

For more information on managing project security, see Project Security Management in the Users and Identity Management Guide.

4.2.3. Creating, assigning, and releasing floating IP addresses

By default, an instance is given an internal IP address when it is first created. However, you can enable access through the public network by creating and assigning a floating IP address (external address). You can change an instance’s associated IP address regardless of the instance’s state.

Projects have a limited range of floating IP address that can be used (by default, the limit is 50), so you should release these addresses for reuse when they are no longer needed. Floating IP addresses can only be allocated from an existing floating IP pool, see Create Floating IP Pools in the Networking Guide.

4.2.3.1. Allocating a floating IP to the project

  1. In the dashboard, select Project > Compute > Access & Security.
  2. On the Floating IPs tab, click Allocate IP to Project.
  3. Select a network from which to allocate the IP address in the Pool field.
  4. Click Allocate IP.

4.2.3.2. Assigning a floating IP

  1. In the dashboard, select Project > Compute > Access & Security.
  2. On the Floating IPs tab, click the address' Associate button.
  3. Select the address to be assigned in the IP address field.

    Note

    If no addresses are available, you can click the + button to create a new address.

  4. Select the instance to be associated in the Port to be Associated field. An instance can only be associated with one floating IP address.
  5. Click Associate.

4.2.3.3. Releasing a floating IP

  1. In the dashboard, select Project > Compute > Access & Security.
  2. On the Floating IPs tab, click the address' menu arrow (next to the Associate/Disassociate button).
  3. Select Release Floating IP.

4.2.4. Logging in to an instance

Prerequisites:

To first load the key pair file into SSH, and then use ssh without naming it:

  1. Change the permissions of the generated key-pair certificate.

    $ chmod 600 os-key.pem
  2. Check whether ssh-agent is already running:

    # ps -ef | grep ssh-agent
  3. If not already running, start it up with:

    # eval `ssh-agent`
  4. On your local machine, load the key-pair certificate into SSH. For example:

    $ ssh-add ~/.ssh/os-key.pem
  5. You can now SSH into the file with the user supplied by the image.

The following example command shows how to SSH into the Red Hat Enterprise Linux guest image with the user cloud-user:

$ ssh cloud-user@192.0.2.24
Note

You can also use the certificate directly. For example:

$ ssh -i /myDir/os-key.pem cloud-user@192.0.2.24

4.2.5. Injecting an admin password into an instance

You can inject an admin (root) password into an instance using the following procedure.

  1. In the /etc/openstack-dashboard/local_settings file, set the change_set_password parameter value to True.

    can_set_password: True
  2. Set the inject_password parameter to "True" in your Compute environment file.

    inject_password=true
  3. Restart the Compute service.

    # service nova-compute restart

When you use the nova boot command to launch a new instance, the output of the command displays an adminPass parameter. You can use this password to log into the instance as the root user.

The Compute service overwrites the password value in the /etc/shadow file for the root user. This procedure can also be used to activate the root account for the KVM guest images. For more information on how to use KVM guest images, see Section 1.2.1.1, “Using a KVM guest image with Red Hat OpenStack Platform”

You can also set a custom password from the dashboard. To enable this, run the following command after you have set can_set_password parameter to true.

# systemctl restart httpd.service

The newly added admin password fields are as follows:

dashboard

These fields can be used when you launch or rebuild an instance.

4.3. Managing flavors

Each created instance is given a flavor (resource template), which determines the instance’s size and capacity. Flavors can also specify secondary ephemeral storage, swap disk, metadata to restrict usage, or special project access (none of the default flavors have these additional attributes defined).

Table 4.3. Default Flavors

NamevCPUsRAMRoot Disk Size

m1.tiny

1

512 MB

1 GB

m1.small

1

2048 MB

20 GB

m1.medium

2

4096 MB

40 GB

m1.large

4

8192 MB

80 GB

m1.xlarge

8

16384 MB

160 GB

The majority of end users will be able to use the default flavors. However, you can create and manage specialized flavors. For example, you can:

  • Change default memory and capacity to suit the underlying hardware needs.
  • Add metadata to force a specific I/O rate for the instance or to match a host aggregate.
Note

Behavior set using image properties overrides behavior set using flavors (for more information, see Section 1.2, “Managing images”).

4.3.1. Updating configuration permissions

By default, only administrators can create flavors or view the complete flavor list (select Admin > System > Flavors). To allow all users to configure flavors, specify the following in the /etc/nova/policy.json file (nova-api server):

"compute_extension:flavormanage": "",

4.3.2. Creating a flavor

  1. As an admin user in the dashboard, select Admin > System > Flavors.
  2. Click Create Flavor, and specify the following fields:

    Table 4.4. Flavor Options

    TabFieldDescription

    Flavor Information

    Name

    Unique name.

     

    ID

    Unique ID. The default value, auto, generates a UUID4 value, but you can also manually specify an integer or UUID4 value.

     

    VCPUs

    Number of virtual CPUs.

     

    RAM (MB)

    Memory (in megabytes).

     

    Root Disk (GB)

    Ephemeral disk size (in gigabytes); to use the native image size, specify 0. This disk is not used if Instance Boot Source=Boot from Volume.

     

    Epehemeral Disk (GB)

    Secondary ephemeral disk size (in gigabytes) available to an instance. This disk is destroyed when an instance is deleted.

    The default value is 0, which implies that no ephemeral disk is created.

     

    Swap Disk (MB)

    Swap disk size (in megabytes).

    Flavor Access

    Selected Projects

    Projects which can use the flavor. If no projects are selected, all projects have access (Public=Yes).

  3. Click Create Flavor.

4.3.3. Updating general attributes

  1. As an admin user in the dashboard, select Admin > System > Flavors.
  2. Click the flavor’s Edit Flavor button.
  3. Update the values, and click Save.

4.3.4. Updating flavor metadata

In addition to editing general attributes, you can add metadata to a flavor (extra_specs), which can help fine-tune instance usage. For example, you might want to set the maximum-allowed bandwidth or disk writes.

  • Pre-defined keys determine hardware support or quotas. Pre-defined keys are limited by the hypervisor you are using (for libvirt, see Table 4.5, “Libvirt Metadata”).
  • Both pre-defined and user-defined keys can determine instance scheduling. For example, you might specify SpecialComp=True; any instance with this flavor can then only run in a host aggregate with the same key-value combination in its metadata (see Section 4.4, “Managing host aggregates”).

4.3.4.1. Viewing metadata

  1. As an admin user in the dashboard, select Admin > System > Flavors.
  2. Click the flavor’s Metadata link (Yes or No). All current values are listed on the right-hand side under Existing Metadata.

4.3.4.2. Adding metadata

You specify a flavor’s metadata using a key/value pair.

  1. As an admin user in the dashboard, select Admin > System > Flavors.
  2. Click the flavor’s Metadata link (Yes or No). All current values are listed on the right-hand side under Existing Metadata.
  3. Under Available Metadata, click on the Other field, and specify the key you want to add (see Table 4.5, “Libvirt Metadata”).
  4. Click the + button; you can now view the new key under Existing Metadata.
  5. Fill in the key’s value in its right-hand field.

    flavor metadata

  6. When finished with adding key-value pairs, click Save.

Table 4.5. Libvirt Metadata

KeyDescription

hw:action

Action that configures support limits per instance. Valid actions are:

  • cpu_max_sockets - Maximum supported CPU sockets.
  • cpu_max_cores - Maximum supported CPU cores.
  • cpu_max_threads - Maximum supported CPU threads.
  • cpu_sockets - Preferred number of CPU sockets.
  • cpu_cores - Preferred number of CPU cores.
  • cpu_threads - Preferred number of CPU threads.
  • serial_port_count - Maximum serial ports per instance.

Example: hw:cpu_max_sockets=2

hw:NUMA_def

Definition of NUMA topology for the instance. For flavors whose RAM and vCPU allocations are larger than the size of NUMA nodes in the compute hosts, defining NUMA topology enables hosts to better utilize NUMA and improve performance of the guest OS. NUMA definitions defined through the flavor override image definitions. Valid definitions are:

  • numa_nodes - Number of NUMA nodes to expose to the instance. Specify 1 to ensure image NUMA settings are overridden.
  • numa_cpus.0 - Mapping of vCPUs N-M to NUMA node 0 (comma-separated list).
  • numa_cpus.1 - Mapping of vCPUs N-M to NUMA node 1 (comma-separated list).
  • numa_mem.0 - Mapping N MB of RAM to NUMA node 0.
  • numa_mem.1 - Mapping N MB of RAM to NUMA node 1.
  • numa_cpu.N and numa_mem.N are only valid if numa_nodes is set. Additionally, they are only required if the instance’s NUMA nodes have an asymetrical allocation of CPUs and RAM (important for some NFV workloads).
Note

If the values of numa_cpu or numa_mem.N specify more than that available, an exception is raised.

Example when the instance has 8 vCPUs and 4GB RAM:

  • hw:numa_nodes=2
  • hw:numa_cpus.0=0,1,2,3,4,5
  • hw:numa_cpus.1=6,7
  • hw:numa_mem.0=3072
  • hw:numa_mem.1=1024

The scheduler looks for a host with 2 NUMA nodes with the ability to run 6 CPUs + 3072 MB, or 3 GB, of RAM on one node, and 2 CPUS + 1024 MB, or 1 GB, of RAM on another node. If a host has a single NUMA node with capability to run 8 CPUs and 4 GB of RAM, it will not be considered a valid match.

hw:watchdog_action

An instance watchdog device can be used to trigger an action if the instance somehow fails (or hangs). Valid actions are:

  • disabled - The device is not attached (default value).
  • pause - Pause the instance.
  • poweroff - Forcefully shut down the instance.
  • reset - Forcefully reset the instance.
  • none - Enable the watchdog, but do nothing if the instance fails.

Example: hw:watchdog_action=poweroff

hw:pci_numa_affinity_policy

You can use this parameter to specify the NUMA affinity policy for PCI passthrough devices and SR-IOV interfaces. Set to one of the following valid values:

  • required: The Compute service only creates an instance that requests a PCI device when at least one of the NUMA nodes of the instance has affinity with the PCI device. This option provides the best performance.
  • preferred: The Compute service attempts a best effort selection of PCI devices based on NUMA affinity. If this is not possible, then the Compute service schedules the instance on a NUMA node that has no affinity with the PCI device.
  • legacy: (Default) The Compute service creates instances that request a PCI device when either:

    • The PCI device has affinity with at least one of the NUMA nodes; or
    • The PCI devices do not provide information on their NUMA affinities.

Example: hw:pci_numa_affinity_policy=required

hw_rng:action

A random-number generator device can be added to an instance using its image properties (see hw_rng_model in the "Command-Line Interface Reference" in Red Hat OpenStack Platform documentation).

If the device has been added, valid actions are:

  • allowed - If True, the device is enabled; if False, disabled. By default, the device is disabled.
  • rate_bytes - Maximum number of bytes the instance’s kernel can read from the host to fill its entropy pool every rate_period (integer).
  • rate_period - Duration of the read period in seconds (integer).

Example: hw_rng:allowed=True.

hw_video:ram_max_mb

Maximum permitted RAM to be allowed for video devices (in MB).

Example: hw:ram_max_mb=64

quota:option

Enforcing limit for the instance. Valid options are:

  • cpu_period - Time period for enforcing cpu_quota (in microseconds). Within the specified cpu_period, each vCPU cannot consume more than cpu_quota of runtime. The value must be in range [1000, 1000000]; 0 means no value.
  • cpu_quota - Maximum allowed bandwidth (in microseconds) for the vCPU in each `cpu_period. The value must be in range [1000, 18446744073709551]. 0 means no value; a negative value means that the vCPU is not controlled. cpu_quota and cpu_period can be used to ensure that all vCPUs run at the same speed.
  • cpu_shares - Share of CPU time for the domain. The value only has meaning when weighted against other machine values in the same domain. That is, an instance with a flavor with 200 will get twice as much machine time as an instance with 100.
  • disk_read_bytes_sec - Maximum disk reads in bytes per second.
  • disk_read_iops_sec - Maximum read I/O operations per second.
  • disk_write_bytes_sec - Maximum disk writes in bytes per second.
  • disk_write_iops_sec - Maximum write I/O operations per second.
  • disk_total_bytes_sec - Maximum total throughput limit in bytes per second.
  • disk_total_iops_sec - Maximum total I/O operations per second.
  • vif_inbound_average - Desired average of incoming traffic.
  • vif_inbound_burst - Maximum amount of traffic that can be received at vif_inbound_peak speed.
  • vif_inbound_peak - Maximum rate at which incoming traffic can be received.
  • vif_outbound_average - Desired average of outgoing traffic.
  • vif_outbound_burst - Maximum amount of traffic that can be sent at vif_outbound_peak speed.
  • vif_outbound_peak - Maximum rate at which outgoing traffic can be sent.

Example: quota:vif_inbound_average=10240

In addition, the VMware driver supports the following quota options, which control upper and lower limits for CPUs, RAM, disks, and networks, as well as shares, which can be used to control relative allocation of available resources among tenants:

  • cpu_limit - Maximum CPU frequency available to a virtual machine (in MHz).
  • cpu_reservation - Guaranteed minimum amount of CPU resources available to a virtual machine (in MHz).
  • cpu_shares_level - CPU allocation level (shares) in the case of contention. Possible values are high, normal, low, and custom.
  • cpu_shares_share - The number of allocated CPU shares. Applicable when cpu_shares_level is set to custom.
  • memory_limit - Maximum amount of RAM available to a virtual machine (in MB).
  • memory_reservation - Guaranteed minimum amount of RAM available to a virtual machine (in MB).
  • memory_shares_level - RAM allocation level (shares) in the case of contention. Possible values are high, normal, low, and custom.
  • memory_shares_share - The number of allocated RAM shares. Applicable when memory_shares_level is set to custom.
  • disk_io_limit - Maximum I/O utilization by a virtual machine (in I/O operations per second).
  • disk_io_reservation - Guaranteed minimum amount of disk resources available to a virtual machine (in I/O operations per second).
  • disk_io_shares_level - I/O allocation level (shares) in the case of contention. Possible values are high, normal, low, and custom.
  • disk_io_shares_share - The number of allocated I/O shares. Applicable when disk_io_shares_level is set to custom.
  • vif_limit - Maximum network bandwidth available to a virtual network adapter (in Mbps).
  • vif_reservation - Guaranteed minimum network bandwidth available to a virtual network adapter (in Mbps).
  • vif_shares_level - Network bandwidth allocation level (shares) in the case of contention. Possible values are high, normal, low, and custom.
  • vif_shares_share - The number of allocated network bandwidth shares. Applicable when vif_shares_level is set to custom.

4.4. Managing host aggregates

A single Compute deployment can be partitioned into logical groups for performance or administrative purposes. OpenStack uses the following terms:

  • Host aggregates - A host aggregate creates logical units in a OpenStack deployment by grouping together hosts. Aggregates are assigned Compute hosts and associated metadata; a host can be in more than one host aggregate. Only administrators can see or create host aggregates.

    An aggregate’s metadata is commonly used to provide information for use with the Compute scheduler (for example, limiting specific flavors or images to a subset of hosts). Metadata specified in a host aggregate will limit the use of that host to any instance that has the same metadata specified in its flavor.

    Administrators can use host aggregates to handle load balancing, enforce physical isolation (or redundancy), group servers with common attributes, or separate out classes of hardware. When you create an aggregate, a zone name must be specified, and it is this name which is presented to the end user.

  • Availability zones - An availability zone is the end-user view of a host aggregate. An end user cannot view which hosts make up the zone, nor see the zone’s metadata; the user can only see the zone’s name.

    End users can be directed to use specific zones which have been configured with certain capabilities or within certain areas.

4.4.1. Enabling host aggregate scheduling

By default, host-aggregate metadata is not used to filter instance usage. You must update the Compute scheduler’s configuration to enable metadata usage:

  1. Open your Compute environment file.
  2. Add the following values to the NovaSchedulerDefaultFilters parameter, if they are not already present:

    • AggregateInstanceExtraSpecsFilter for host aggregate metadata.

      Note

      Scoped specifications must be used for setting flavor extra_specs when specifying both AggregateInstanceExtraSpecsFilter and ComputeCapabilitiesFilter filters as values of the same NovaSchedulerDefaultFilters parameter, otherwise the ComputeCapabilitiesFilter will fail to select a suitable host. See Table 4.7, “Scheduling Filters” for further details.

    • AvailabilityZoneFilter for availability zone host specification when launching an instance.
  3. Save the configuration file.
  4. Deploy the overcloud.

4.4.2. Viewing availability zones or host aggregates

As an admin user in the dashboard, select Admin > System > Host Aggregates. All currently defined aggregates are listed in the Host Aggregates section; all zones are in the Availability Zones section.

4.4.3. Adding a host aggregate

  1. As an admin user in the dashboard, select Admin > System > Host Aggregates. All currently defined aggregates are listed in the Host Aggregates section.
  2. Click Create Host Aggregate.
  3. Add a name for the aggregate in the Name field, and a name by which the end user should see it in the Availability Zone field.
  4. Click Manage Hosts within Aggregate.
  5. Select a host for use by clicking its + icon.
  6. Click Create Host Aggregate.

4.4.4. Updating a host aggregate

  1. As an admin user in the dashboard, select Admin > System > Host Aggregates. All currently defined aggregates are listed in the Host Aggregates section.
  2. To update the instance’s Name or Availability zone:

    • Click the aggregate’s Edit Host Aggregate button.
    • Update the Name or Availability Zone field, and click Save.
  3. To update the instance’s Assigned hosts:

    • Click the aggregate’s arrow icon under Actions.
    • Click Manage Hosts.
    • Change a host’s assignment by clicking its + or - icon.
    • When finished, click Save.
  4. To update the instance’s Metadata:

    • Click the aggregate’s arrow icon under Actions.
    • Click the Update Metadata button. All current values are listed on the right-hand side under Existing Metadata.
    • Under Available Metadata, click on the Other field, and specify the key you want to add. Use predefined keys (see Table 4.6, “Host Aggregate Metadata”) or add your own (which will only be valid if exactly the same key is set in an instance’s flavor).
    • Click the + button; you can now view the new key under Existing Metadata.

      Note

      Remove a key by clicking its - icon.

    • Click Save.

      Table 4.6. Host Aggregate Metadata

      KeyDescription

      filter_tenant_id

      If specified, the aggregate only hosts this tenant (project). Depends on the AggregateMultiTenancyIsolation filter being set for the Compute scheduler.

4.4.5. Deleting a host aggregate

  1. As an admin user in the dashboard, select Admin > System > Host Aggregates. All currently defined aggregates are listed in the Host Aggregates section.
  2. Remove all assigned hosts from the aggregate:

    1. Click the aggregate’s arrow icon under Actions.
    2. Click Manage Hosts.
    3. Remove all hosts by clicking their - icon.
    4. When finished, click Save.
  3. Click the aggregate’s arrow icon under Actions.
  4. Click Delete Host Aggregate in this and the next dialog screen.

4.5. Scheduling hosts

The Compute scheduling service determines on which host (or host aggregate), an instance will be placed. As an administrator, you can influence where the scheduler will place an instance. For example, you might want to limit scheduling to hosts in a certain group or with the right RAM.

You can configure the following components:

  • Filters - Determine the initial set of hosts on which an instance might be placed (see Section 4.5.1, “Configuring scheduling filters”).
  • Weights - When filtering is complete, the resulting set of hosts are prioritized using the weighting system. The highest weight has the highest priority (see Section 4.5.2, “Configuring scheduling weights”).
  • Scheduler service - There are a number of configuration options in the /var/lib/config-data/puppet-generated/<nova_container>/etc/nova/nova.conf file (on the scheduler host), which determine how the scheduler executes its tasks, and handles weights and filters.

In the following diagram, both host 1 and 3 are eligible after filtering. Host 1 has the highest weight and therefore has the highest priority for scheduling.

Scheduling Hosts

4.5.1. Configuring scheduling filters

You define the filters you want the scheduler to use by adding or removing filters from the NovaSchedulerDefaultFilters parameter in your Compute environment file.

The default configuration runs the following filters in the scheduler:

  • RetryFilter
  • AvailabilityZoneFilter
  • ComputeFilter
  • ComputeCapabilitiesFilter
  • ImagePropertiesFilter
  • ServerGroupAntiAffinityFilter
  • ServerGroupAffinityFilter

Some filters use information in parameters passed to the instance in:

The following table lists all the available filters.

Table 4.7. Scheduling Filters

FilterDescription

AggregateImagePropertiesIsolation

Only passes hosts in host aggregates whose metadata matches the instance’s image metadata; only valid if a host aggregate is specified for the instance. For more information, see Section 1.2.1, “Creating an image”.

AggregateInstanceExtraSpecsFilter

Metadata in the host aggregate must match the host’s flavor metadata. For more information, see Section 4.3.4, “Updating flavor metadata”.

 

This filter can only be specified in the same NovaSchedulerDefaultFilters parameter as ComputeCapabilitiesFilter when you scope your flavor extra_specs keys by prefixing them with the correct namespace:

  • ComputeCapabilitiesFilter namespace = "capabilities:"
  • AggregateInstanceExtraSpecsFilter namespace = "aggregate_instance_extra_specs:"

AggregateMultiTenancyIsolation

A host with the specified filter_tenant_id can only contain instances from that tenant (project).

Note

The tenant can still place instances on other hosts.

AllHostsFilter

Passes all available hosts (however, does not disable other filters).

AvailabilityZoneFilter

Filters using the instance’s specified availability zone.

ComputeCapabilitiesFilter

Ensures Compute metadata is read correctly. Anything before the : is read as a namespace. For example, quota:cpu_period uses quota as the namespace and cpu_period as the key.

ComputeFilter

Passes only hosts that are operational and enabled.

DifferentHostFilter

Enables an instance to build on a host that is different from one or more specified hosts. Specify different hosts using the nova boot option --different_host option.

ImagePropertiesFilter

Only passes hosts that match the instance’s image properties. For more information, see Section 1.2.1, “Creating an image”.

IsolatedHostsFilter

Passes only isolated hosts running isolated images that are specified using isolated_hosts and isolated_images (comma-separated values).

JsonFilter

Recognises and uses an instance’s custom JSON filters:

  • Valid operators are: =, <, >, in, ⇐, >=, not, or, and
  • Recognised variables are: $free_ram_mb, $free_disk_mb, $total_usable_ram_mb, $vcpus_total, $vcpus_used
 

The filter is specified as a query hint in the nova boot command. For example:

--hint query='['>=', '$free_disk_mb', 200 * 1024]'

MetricsFilter

Use this filter to limit scheduling to Compute nodes that report the metrics configured by using metrics/weight_setting.

Tip

By default, the Compute scheduling service updates the metrics every 60 seconds. To ensure the metrics are up-to-date, you can increase the frequency at which the metrics data is refreshed using the update_resources_interval configuration option. For example, use the following configuration to refresh the metrics data every 2 seconds:

parameter_defaults:
  ComputeExtraConfig:
    nova::config::nova_config:
      DEFAULT/update_resources_interval:
        value: '2'

NUMATopologyFilter

Filters out hosts based on its NUMA topology. If the instance has no topology defined, any host can be used. The filter tries to match the exact NUMA topology of the instance to those of the host (it does not attempt to pack the instance onto the host). The filter also looks at the standard over-subscription limits for each NUMA node, and provides limits to the compute host accordingly.

PCIWeigher

The weigher can compute the weight based on the number of PCI devices on the host and the number of PCI devices requested by an instance. For example, if there are three hosts available, one with a single PCI device, one with multiple PCI devices and one without any PCI devices, then Compute should prioritize these hosts based on the demands of the instance. The first host should be preferred if the instance requests one PCI device, the second host if the instance requires multiple PCI devices and the third host if the instances does not request a PCI device.

For more information, see Reserve NUMA Nodes with PCI Devices

RetryFilter

Filters out hosts that have failed a scheduling attempt; valid if scheduler_max_attempts is greater than zero (defaults to "3").

SameHostFilter

Passes one or more specified hosts; specify hosts for the instance using the --hint same_host option for nova boot.

ServerGroupAffinityFilter

Only passes hosts for a specific server group:

  • Give the server group the affinity policy (nova server-group-create --policy affinity groupName).
  • Build the instance with that group (nova boot option --hint group=UUID)

ServerGroupAntiAffinityFilter

Only passes hosts in a server group that do not already host an instance:

  • Give the server group the anti-affinity policy (nova server-group-create --policy anti-affinity groupName).
  • Build the instance with that group (nova boot option --hint group=UUID).

SimpleCIDRAffinityFilter

Only passes hosts on the specified IP subnet range specified by the instance’s cidr and build_new_host_ip hints. Example:

--hint build_near_host_ip=192.0.2.0 --hint cidr=/24

4.5.2. Configuring scheduling weights

Hosts can be weighted for scheduling; the host with the largest weight (after filtering) is selected. All weighers are given a multiplier that is applied after normalising the node’s weight. A node’s weight is calculated as:

w1_multiplier * norm(w1) + w2_multiplier * norm(w2) + ...

You can configure weight options in the Compute node’s configuration file.

4.5.2.1. Configure Weight Options for Hosts

You can define the host weighers you would like the scheduler to use in the [DEFAULT] scheduler_weight_classes option. Valid weighers are:

  • nova.scheduler.weights.ram - Weighs the host’s available RAM.
  • nova.scheduler.weights.metrics - Weighs the host’s metrics.
  • nova.scheduler.weights.affinity - Weighs the host’s proximity to other hosts in the given server group.
  • nova.scheduler.weights.all_weighers - Uses all host weighers (default).

Table 4.8. Host Weight Options

WeigherOptionDescription

All

[DEFAULT] scheduler_host_subset_size

Defines the subset size from which a host is selected (integer); must be at least 1. A value of 1 selects the first host returned by the weighing functions. Any value less than 1 is ignored and 1 is used instead (integer value).

affinity

[default] soft_affinity_weight_multiplier

Used for weighing hosts for group soft-affinity. Should be a positive floating-point number, because a negative value results in the opposite behavior, which is normally controlled by soft_anti_affinity_weight_multiplier.

affinity

[default] soft_anti_affinity_weight_multiplier

Used for weighing hosts for group soft-anti-affinity. Should be a positive floating-point number, because a negative value results in the opposite behavior, which is normally controlled by soft_affinity_weight_multiplier.

metrics

[metrics] required

Specifies how to handle metrics in [metrics] weight_setting that are unavailable:

  • True- Metrics are required; if unavailable, an exception is raised. To avoid the exception, use the MetricFilter filter in the scheduler_default_filters option.
  • False - The unavailable metric is treated as a negative factor in the weighing process; the returned value is set by weight_of_unavailable.

metrics

[metrics] weight_of_unavailable

Used as the weight if any metric in [metrics] weight_setting is unavailable; valid if required=False.

metrics

[metrics] weight_multiplier

Mulitplier used for weighing metrics. By default, weight_multiplier=1.0 and spreads instances across possible hosts. If this value is negative, the host with lower metrics is prioritized, and instances are stacked in hosts.

metrics

[metrics] weight_setting

Specifies metrics and the ratio with which they are weighed; use a comma-separated list of metric=ratio pairs. Valid metric names are:

  • cpu.frequency - Current CPU frequency
  • cpu.user.time - CPU user mode time
  • cpu.kernel.time - CPU kernel time
  • cpu.idle.time - CPU idle time
  • cpu.iowait.time - CPU I/O wait time
  • cpu.user.percent - CPU user mode percentage
  • cpu.kernel.percent - CPU kernel percentage
  • cpu.idle.percent - CPU idle percentage
  • cpu.iowait.percent - CPU I/O wait percentage
  • cpu.percent - Generic CPU utilization

Example: weight_setting=cpu.user.time=1.0

ram

[DEFAULT] ram_weight_multiplier

Multiplier for RAM (floating point). By default, ram_weight_multiplier=1.0 and spreads instances across possible hosts. If this value is negative, the host with less RAM is prioritized, and instances are stacked in hosts.

4.5.3. Reserving NUMA nodes with PCI devices

Compute uses the filter scheduler to prioritize hosts with PCI devices for instances requesting PCI. The hosts are weighted using the PCIWeigher option, based on the number of PCI devices available on the host and the number of PCI devices requested by an instance. If an instance requests PCI devices, then the hosts with more PCI devices are allocated a higher weight than the others. If an instance is not requesting PCI devices, then prioritization does not take place.

This feature is especially useful in the following cases:

  • As an operator, if you want to reserve nodes with PCI devices (typically expensive and with limited resources) for guest instances that request them.
  • As a user launching instances, you want to ensure that PCI devices are available when required.
Note

For this value to be considered, one of the following values must be added to the NovaSchedulerDefaultFilters parameter in your Compute environment file: PciPassthroughFilter or NUMATopologyFilter.

The pci_weight_multiplier configuration option must be a positive value.

4.5.4. Configuring emulator threads to run on dedicated physical CPU

The Compute scheduler determines the CPU resource utilization and places instances based on the number of virtual CPUs (vCPUs) in the flavor. There are a number of hypervisor operations that are performed on the host, on behalf of the guest instance, for example, with QEMU, there are threads used for the QEMU main event loop, asynchronous I/O operations and so on and these operations need to be accounted and scheduled separately.

The libvirt driver implements a generic placement policy for KVM which allows QEMU emulator threads to float across the same physical CPUs (pCPUs) that the vCPUs are running on. This leads to the emulator threads using time borrowed from the vCPUs operations. When you need a guest to have dedicated vCPU allocation, it is necessary to allocate one or more pCPUs for emulator threads. It is therefore necessary to describe to the scheduler any other CPU usage that might be associated with a guest and account for that during placement.

Note

In an NFV deployment, to avoid packet loss, you have to make sure that the vCPUs are never preempted.

Before you enable the emulator threads placement policy on a flavor, check that the following heat parameters are defined as follows:

  • NovaComputeCpuSharedSet: Set this parameter to a list of CPUs defined to run emulator threads.
  • NovaSchedulerDefaultFilters: Include NUMATopologyFilter in the list of defined filters.
Note

You can define or change heat parameter values on an active cluster, and then redeploy for those changes to take effect.

To isolate emulator threads, you must use a flavor configured as follows:

# openstack flavor set FLAVOR-NAME \
--property hw:cpu_policy=dedicated \
--property hw:emulator_threads_policy=share

4.6. Managing instance snapshots

An instance snapshot allows you to create a new image from an instance. This is very convenient for upgrading base images or for taking a published image and customizing it for local use.

The difference between an image that you upload directly to the Image Service and an image that you create by snapshot is that an image created by snapshot has additional properties in the Image Service database. These properties are found in the image_properties table and include the following parameters:

Table 4.9. Snapshot Options

NameValue

image_type

snapshot

instance_uuid

<uuid of instance that was snapshotted>

base_image_ref

<uuid of original image of instance that was snapshotted>

image_location

snapshot

Snapshots allow you to create new instances based on that snapshot, and potentially restore an instance to that state. Moreover, this can be performed while the instance is running.

By default, a snapshot is accessible to the users and projects that were selected while launching an instance that the snapshot is based on.

4.6.1. Creating an instance snapshot

Note

If you intend to use an instance snapshot as a template to create new instances, you must ensure that the disk state is consistent. Before you create a snapshot, set the snapshot image metadata property os_require_quiesce=yes. For example,

$ glance image-update IMAGE_ID --property os_require_quiesce=yes

For this to work, the guest should have the qemu-guest-agent package installed, and the image should be created with the metadata property parameter hw_qemu_guest_agent=yes set. For example,

$ glance image-create --name NAME \
--disk-format raw \
--container-format bare \
--file FILE_NAME \
--is-public True \
--property hw_qemu_guest_agent=yes \
--progress

If you unconditionally enable the hw_qemu_guest_agent=yes parameter, then you are adding another device to the guest. This consumes a PCI slot, and will limit the number of other devices you can allocate to the guest. It also causes Windows guests to display a warning message about an unknown hardware device.

For these reasons, setting the hw_qemu_guest_agent=yes parameter is optional, and the parameter should be used for only those images that require the QEMU guest agent.

  1. In the dashboard, select Project > Compute > Instances.
  2. Select the instance from which you want to create a snapshot.
  3. In the Actions column, click Create Snapshot.
  4. In the Create Snapshot dialog, enter a name for the snapshot and click Create Snapshot.

    The Images category now shows the instance snapshot.

To launch an instance from a snapshot, select the snapshot and click Launch.

4.6.2. Managing a snapshot

  1. In the dashboard, select Project > Images.
  2. All snapshots you created, appear under the Project option.
  3. For every snapshot you create, you can perform the following functions, using the dropdown list:

    1. Use the Create Volume option to create a volume and entering the values for volume name, description, image source, volume type, size and availability zone. For more information, see Create a Volume in the Storage Guide.
    2. Use the Edit Image option to update the snapshot image by updating the values for name, description, Kernel ID, Ramdisk ID, Architecture, Format, Minimum Disk (GB), Minimum RAM (MB), public or private. For more information, see Section 1.2.3, “Updating an image”.
    3. Use the Delete Image option to delete the snapshot.

4.6.3. Rebuilding an instance to a state in a snapshot

In an event that you delete an instance on which a snapshot is based, the snapshot still stores the instance ID. You can check this information using the nova image-list command and use the snapshot to restore the instance.

  1. In the dashboard, select Project > Compute > Images.
  2. Select the snapshot from which you want to restore the instance.
  3. In the Actions column, click Launch Instance.
  4. In the Launch Instance dialog, enter a name and the other details for the instance and click Launch.

For more information on launching an instance, see Section 4.1.2, “Launching an instance”.

4.6.4. Consistent snapshots

Previously, file systems had to be quiesced manually (fsfreeze) before taking a snapshot of active instances for consistent backups.

Compute’s libvirt driver automatically requests the QEMU Guest Agent to freeze the file systems (and applications if fsfreeze-hook is installed) during an image snapshot. Support for quiescing file systems enables scheduled, automatic snapshots at the block device level.

This feature is only valid if the QEMU Guest Agent is installed (qemu-ga) and the image metadata enables the agent (hw_qemu_guest_agent=yes)

Note

Snapshots should not be considered a substitute for an actual system backup.

4.7. Using rescue mode for instances

Compute has a method to reboot a virtual machine in rescue mode. Rescue mode provides a mechanism for access when the virtual machine image renders the instance inaccessible. A rescue virtual machine allows a user to fix their virtual machine by accessing the instance with a new root password. This feature is useful if an instance’s filesystem is corrupted. By default, rescue mode starts an instance from the initial image attaching the current boot disk as a secondary one.

4.7.1. Preparing an image for a rescue mode instance

Due to the fact that both the boot disk and the disk for rescue mode have same UUID, sometimes the virtual machine can be booted from the boot disk instead of the disk for rescue mode.

To avoid this issue, you should create a new image as rescue image based on the procedure in Section 1.2.1, “Creating an image”:

Note

The rescue image is stored in glance and configured in the nova.conf as a default, or you can select when you do the rescue.

4.7.1.1. Rescuing image if using ext4 filesystem

When the base image uses ext4 filesystem, you can create a rescue image from it using the following procedure:

  1. Change the UUID to a random value using the tune2fs command:

    # tune2fs -U random /dev/DEVICE_NODE

    Here DEVICE_NODE is the root device node (for example, sda, vda, and so on).

  2. Verify the details of the filesystem, including the new UUID:

    # tune2fs -l
  3. Update the /etc/fstab to use the new UUID. You may need to repeat this for any additional partitions you have, that are mounted in the fstab by UUID.
  4. Update the /boot/grub2/grub.conf file and update the UUID parameter with the new UUID of the root disk.
  5. Shut down and use this image as your rescue image. This will cause the rescue image to have a new random UUID that will not conflict with the instance that you are rescuing.
Note

The XFS filesystem cannot change the UUID of the root device on the running virtual machine. Reboot the virtual machine until the virtual machine is launched from the disk for rescue mode.

4.7.2. Adding the rescue image to the OpenStack Image Service

When you have completed modifying the UUID of your image, use the following commands to add the generated rescue image to the OpenStack Image service:

  1. Add the rescue image to the Image service:

    # glance image-create --name IMAGE_NAME --disk-format qcow2 \
      --container-format bare --is-public True --file IMAGE_PATH

    Here IMAGE_NAME is the name of the image, IMAGE_PATH is the location of the image.

  2. Use the image-list command to obtain the IMAGE_ID required for launching an instace in the rescue mode.

    # glance image-list

You can also upload an image using the OpenStack Dashboard, see Section 1.2.2, “Uploading an image”.

4.7.3. Launching an instance in rescue mode

  1. Since you need to rescue an instance with a specific image, rather than the default one, use the --image parameter:

    # nova rescue --image IMAGE_ID VIRTUAL_MACHINE_ID

    Here IMAGE_ID is the ID of the image you want to use and VIRTUAL_MACHINE_ID is ID of a virtual machine that you want to rescue.

    Note

    The nova rescue command allows an instance to perform a soft shut down. This allows the guest operating system to perform a controlled shutdown before the instance is powered off. The shut down behavior is configured using shutdown_timeout in your Compute configuration file. The value stands for the overall period (in seconds) a guest operation system is allowed to complete the shutdown. The default timeout is 60 seconds.

    The timeout value can be overridden on a per image basis by means of os_shutdown_timeout that is an image metadata setting allowing different types of operating systems to specify how much time they need to shut down cleanly.

  2. Reboot the virtual machine.
  3. Confirm the status of the virtual machine is RESCUE on the controller node by using nova list command or by using dashboard.
  4. Log in to the new virtual machine dashboard by using the password for rescue mode.

You can now make the necessary changes to your instance to fix any issues.

4.7.4. Unrescuing an instance

You can unrescue the fixed instance to restart it from the boot disk.

  1. Execute the following commands on the controller node.

    # nova unrescue VIRTUAL_MACHINE_ID

    Here VIRTUAL_MACHINE_ID is ID of a virtual machine that you want to unrescue.

The status of your instance returns to ACTIVE once the unrescue operation has completed successfully.

4.8. Setting a configuration drive for instances

You can use the config-drive parameter to present a read-only drive to your instances. This drive can contain selected files that are then accessible to the instance. The configuration drive is attached to the instance at boot, and is presented to the instance as a partition. Configuration drives are useful when combined with cloud-init (for server bootstrapping), and when you want to pass large files to your instances.

4.8.1. Configuration drive options

Use your Compute environment file to set the following configuration drive parameters:

  • config_drive_format - sets the format of the drive, and accepts the options iso9660 and vfat. By default, it uses iso9660.
  • force_config_drive - this forces the configuration drive to be presented to all instances. Set to "True".
  • mkisofs_cmd - specifies the command to use for ISO file creation. This value must not be changed, as only genisoimage is supported.

4.8.2. Using a configuration drive

An instance attaches its configuration drive at boot time. This is enabled by the --config-drive option. For example, this command creates a new instance named test-instance01 and attaches a drive containing a file named /root/user-data.txt:

# nova boot --flavor m1.tiny --config-drive true --file /root/user-data.txt=/root/user-data.txt --image cirros test-instance01

Once the instance has booted, you can log in to it and see a file named /root/user-data.txt.

Note

You can use the configuration drive as a source for cloud-init information. During the initial instance boot, cloud-init can automatically mount the configuration drive and run the setup scripts.

Chapter 5. Migrating virtual machine instances between Compute nodes

You sometimes need to migrate instances from one Compute node to another Compute node in the overcloud, to perform maintenance, rebalance the workload, or replace a failed or failing node.

Compute node maintenance
If you need to temporarily take a Compute node out of service, for instance, to perform hardware maintenance or repair, kernel upgrades and software updates, you can migrate instances running on the Compute node to another Compute node.
Failing Compute node
If a Compute node is about to fail and you need to service it or replace it, you can migrate instances from the failing Compute node to a healthy Compute node.
Failed Compute nodes
If a Compute node has already failed, you can evacuate the instances. You can rebuild instances from the original image on another Compute node, using the same name, UUID, network addresses, and any other allocated resources the instance had before the Compute node failed.
Workload rebalancing
You can migrate one or more instances to another Compute node to rebalance the workload. For example, you can consolidate instances on a Compute node to conserve power, migrate instances to a Compute node that is physically closer to other networked resources to reduce latency, or distribute instances across Compute nodes to avoid hot spots and increase resiliency.

Director configures all Compute nodes to provide secure migration. All Compute nodes also require a shared SSH key to provide the users of each host with access to other Compute nodes during the migration process. Director creates this key using the OS::TripleO::Services::NovaCompute composable service. This composable service is one of the main services included on all Compute roles by default. For more information, see Composable Services and Custom Roles in the Advanced Overcloud Customization guide.

Note

If you have a functioning Compute node, and you want to make a copy of an instance for backup purposes, or to copy the instance to a different environment, follow the procedure in Importing virtual machines into the overcloud in the Director Installation and Usage guide.

5.1. Migration types

Red Hat OpenStack Platform (RHOSP) supports the following types of migration.

Cold migration

Cold migration, or non-live migration, involves shutting down a running instance before migrating it from the source Compute node to the destination Compute node.

Cold Migration

Cold migration involves some downtime for the instance. The migrated instance maintains access to the same volumes and IP addresses.

Note

Cold migration requires that both the source and destination Compute nodes are running.

Live migration

Live migration involves moving the instance from the source Compute node to the destination Compute node without shutting it down, and while maintaining state consistency.

Live Migration

Live migrating an instance involves little or no perceptible downtime. In some cases, instances cannot use live migration. For more information, see Migration Constraints.

Note

Live migration requires that both the source and destination Compute nodes are running.

Evacuation

If you need to migrate instances because the source Compute node has already failed, you can evacuate the instances.

5.2. Migration constraints

In some cases, migrating instances involves additional constraints. Migration constraints typically arise with block migration, configuration disks, or when one or more instances access physical hardware on the Compute node.

CPU constraints

The source and destination Compute nodes must have the same CPU architecture. For example, Red Hat does not support migrating an instance from an x86_64 CPU to a ppc64le CPU. In some cases, the CPU of the source and destination Compute node must match exactly, such as instances that use CPU host passthrough. In all cases, the CPU features of the destination node must be a superset of the CPU features on the source node. Using CPU pinning introduces additional constraints. For more information, see Live migration constraints.

Memory constraints

The destination Compute node must have sufficient available RAM. Memory oversubscription can cause migration to fail. Additionally, instances that use a NUMA topology must have sufficient available RAM on the same NUMA node on the destination Compute node.

Block migration constraints

Migrating instances that use disks that are stored locally on a Compute node takes significantly longer than migrating volume-backed instances that use shared storage, such as Red Hat Ceph Storage. This latency arises because OpenStack Compute (nova) migrates local disks block-by-block between the Compute nodes over the control plane network by default. By contrast, volume-backed instances that use shared storage, such as Red Hat Ceph Storage, do not have to migrate the volumes, because each Compute node already has access to the shared storage.

Note

Network congestion in the control plane network caused by migrating local disks or instances that consume large amounts of RAM might impact the performance of other systems that use the control plane network, such as RabbitMQ.

Read-only drive migration constraints

Migrating a drive is supported only if the drive has both read and write capabilities. For example, OpenStack Compute (nova) cannot migrate a CD-ROM drive or a read-only config drive. However, OpenStack Compute (nova) can migrate a drive with both read and write capabilities, including a config drive with a drive format such as vfat.

Live migration constraints

No new operations during migration
To achieve state consistency between the copies of the instance on the source and destination nodes, RHOSP must prevent new operations during live migration. Otherwise, live migration might take a long time or potentially never end if writes to memory occur faster than live migration can replicate the state of the memory.
NUMA, CPU pinning, huge pages and DPDK

OpenStack Compute can live migrate an instance that uses NUMA, CPU pinning or DPDK when the environment meets the following conditions:

  • The destination Compute node must have sufficient capacity on the same NUMA node that the instance uses on the source Compute node. For example, if an instance uses NUMA 0 on overcloud-compute-0, to live migrate the instance to overcloud-compute-1, you must ensure that overcloud-compute-1 has sufficient capacity on NUMA 0 to support the instance.
  • NovaEnableNUMALiveMigration is set to "True" in the Compute configuration. This parameter is enabled by default only when the Compute host is configured for an OVS-DPDK deployment.
  • The NovaSchedulerDefaultFilters parameter in the Compute configuration must include the values AggregateInstanceExtraSpecsFilter and NUMATopologyFilter.
  • CPU Pinning: When a flavor uses CPU pinning, the flavor implicitly introduces a NUMA topology to the instance and maps its CPUs and memory to specific host CPUs and memory. The difference between a simple NUMA topology and CPU pinning is that NUMA uses a range of CPU cores, whereas CPU pinning uses specific CPU cores. For more information, see Configuring CPU pinning with NUMA. To live migrate instances that use CPU pinning, the destination host must be empty and must have equivalent hardware.
  • Data Plane Development Kit (DPDK): When an instance uses DPDK, such as an instance running Open vSwitch with dpdk-netdev, the instance also uses huge pages. Huge pages impose a NUMA topology such that OpenStack Compute (nova) pins the instance to a NUMA node. When you migrate instances that use DPDK, the destination Compute node must have an identical hardware specification and configuration as the source Compute node. Additionally, there must not be any instances running on the destination Compute node to ensure that it preserves the NUMA topology of the source Compute node.

Constraints that preclude live migration

Live migration is not possible when the instance is configured for the following features:

  • Single-root Input/Output Virtualization (SR-IOV): You can assign SR-IOV Virtual Functions (VFs) to instances. However, this prevents live migration. Unlike a regular network device, an SR-IOV VF network device does not have a permanent unique MAC address. The VF network device receives a new MAC address each time the Compute node reboots, or when the scheduler migrates the instance to a new Compute node. Consequently, OpenStack Compute cannot live migrate instances that use SR-IOV. You must cold migrate instances that use SR-IOV.
  • PCI passthrough: QEMU/KVM hypervisors support attaching PCI devices on the Compute node to an instance. Use PCI passthrough to give an instance exclusive access to PCI devices, which appear and behave as if they are physically attached to the operating system of the instance. However, because PCI passthrough involves physical addresses, OpenStack Compute does not support live migration of instances using PCI passthrough.

5.3. Preparing to migrate

Before you migrate one or more instances, you need to determine the Compute node names and the IDs of the instances to migrate.

Procedure

  1. Identify the source Compute node host name and the destination Compute node host name:

    (undercloud) $ source ~/overcloudrc
    (overcloud) $ openstack compute service list
  2. List the instances on the source Compute node and locate the ID of the instance or instances that you want to migrate:

    (overcloud) $ openstack server list --host <source> --all-projects

    Replace <source> with the name or ID of the source Compute node.

  3. Optional: To shut down the source Compute node for maintenance, disable the source Compute node from the undercloud to ensure that the scheduler does not attempt to assign new instances to the source Compute node during maintenance:

    (overcloud) $ source ~/stackrc
    (undercloud) $ openstack compute service set <source> nova-compute --disable

    Replace <source> with the name or ID of the source Compute node.

If you are not migrating NUMA, CPU-pinned or DPDK instances, you are now ready to perform the migration. Follow the required procedure detailed in Cold migrating an instance or Live migrating an instance.

If you are migrating NUMA, CPU-pinned or DPDK instances, you need to prepare the destination node. Complete the procedure detailed in Section 5.4, “Additional preparation for DPDK instances”.

5.4. Additional preparation for DPDK instances

If you are migrating NUMA, CPU-pinned or DPDK instances, you need to prepare the destination node.

Procedure

  1. If the destination Compute node for NUMA, CPU-pinned or DPDK instances is not disabled, disable it to prevent the scheduler from assigning instances to the node:

    (overcloud) $ openstack compute service set <dest> nova-compute --disable

    Replace <dest> with the name or ID of the destination Compute node.

  2. Ensure that the destination Compute node has no instances, except for instances that you previously migrated from the source Compute node when you migrated multiple DPDK or NUMA instances:

    (overcloud) $ openstack server list --host <dest> --all-projects

    Replace <dest> with the name or ID of the destination Compute node.

  3. Ensure that the destination Compute node has sufficient resources to run the NUMA, CPU-pinned or DPDK instance:

    (overcloud) $ openstack host show <dest>
    $ ssh <dest>
    $ numactl --hardware
    $ exit

    Replace <dest> with the name or ID of the destination Compute node.

  4. To discover NUMA information about the source or destination Compute nodes, run the following commands:

    $ ssh root@overcloud-compute-n
    # lscpu && lscpu | grep NUMA
    # virsh nodeinfo
    # virsh capabilities
    # exit

    Use ssh to connect to overcloud-compute-n where overcloud-compute-n is the source or destination Compute node.

  5. If you do not know if an instance uses NUMA, check the flavor of the instance:

    (overcloud) $ openstack server list -c Name -c Flavor --name <vm>
    (overcloud) $ openstack flavor show <flavor>
    • Replace <vm> with the name or ID of the instance.
    • Replace <flavor> with the name or ID of the flavor.

      • If the properties field includes hw:mem_page_size with a value other than any, such as 2MB, 2048 or 1GB, the instance has a NUMA topology.
      • If the properties field includes aggregate_instance_extra_specs:pinned='true', the instance uses CPU pinning.
      • If the properties field includes hw:numa_nodes, the OpenStack Compute (nova) service restricts the instance to a specific NUMA node.
  6. For each instance that uses NUMA, you can retrieve information about the NUMA topology from the underlying Compute node so that you can verify that the NUMA topology on the destination Compute node reflects the NUMA topology of the source Compute node after migration is complete. You can use the following commands to perform this check:

    • To view details about NUMA and CPU pinning, run the following command:

      $ ssh root@overcloud-compute-n
      # virsh vcpuinfo <vm>

      Replace <vm> with the name of the instance.

    • To view details about which NUMA node the instance is using, run the following command:

      $ ssh root@overcloud-compute-n
      # virsh numatune <vm>

      Replace <vm> with the name of the instance.

5.5. Cold migrating an instance

Cold migrating an instance involves stopping the instance and moving it to another Compute node. Cold migration facilitates migration scenarios that live migrating cannot facilitate, such as migrating instances that use PCI passthrough or Single-Root Input/Output Virtualization (SR-IOV). The scheduler automatically selects the destination Compute node. For more information, see Migration Constraints.

Procedure

  1. To cold migrate an instance, run the following command to power off and move the instance:

    (overcloud) $ openstack server migrate <vm> --wait
    • Replace <vm> with the name or ID of the instance to migrate.
    • Specify the --block-migration flag if migrating a locally stored volume.
  2. Wait for migration to complete. See Checking migration status to check the status of the migration.
  3. Check the status of the instance:

    (overcloud) $ openstack server list --all-projects

    A status of "VERIFY_RESIZE" indicates you need to confirm or revert the migration:

    • If the migration worked as expected, confirm it:

      (overcloud) $ openstack server resize --confirm <vm>`

      Replace <vm> with the name or ID of the instance to migrate. A status of "ACTIVE" indicates that the instance is ready to use.

    • If the migration did not work as expected, revert it:

      (overcloud) $ openstack server resize --revert <vm>`

      Replace <vm> with the name or ID of the instance.

  4. Restart the instance:

    (overcloud) $ openstack server start <vm>

    Replace <vm> with the name or ID of the instance.

When you finish migrating the instances, proceed to Completing the migration.

5.6. Live migrating an instance

Live migration moves an instance from a source Compute node to a destination Compute node with a minimal amount of downtime. Live migration might not be appropriate for all instances. For more information, see Section 5.2, “Migration constraints”.

Procedure

  1. To live migrate an instance, specify the instance and the destination Compute node:

    (overcloud) $ openstack server migrate <vm> --live <dest> --wait
    • Replace <vm> with the name or ID of the instance.
    • Replace <dest> with the name or ID of the destination Compute node.

      Note

      The openstack server migrate command covers migrating instances with shared storage, which is the default. Specify the --block-migration flag to migrate a locally stored volume:

      (overcloud) $ openstack server migrate <vm> --live <dest> --wait --block-migration
  2. Confirm that the instance is migrating:

    $ openstack server show <vm>
    
    +----------------------+--------------------------------------+
    | Field                | Value                                |
    +----------------------+--------------------------------------+
    | ...                  | ...                                  |
    | status               | MIGRATING                            |
    | ...                  | ...                                  |
    +----------------------+--------------------------------------+
  3. Wait for migration to complete. See Checking migration status to check the status of the migration.
  4. Check the status of the instance to confirm if the migration was successful:

    (overcloud) $ openstack server list --host <dest> --all-projects

    Replace <dest> with the name or ID of the destination Compute node.

  5. Optional: For instances that use NUMA, CPU-pinning, or DPDK, retrieve information about the NUMA topology from a Compute node to compare it with the NUMA topology that you retrieved during the preparing to migrate procedure. Comparing the NUMA topologies of the source and destination Compute nodes ensures that the source and destination Compute nodes use the same NUMA topology.

    • To view details about NUMA and CPU pinning, run the following command:

      $ ssh root@overcloud-compute-n
      # virsh vcpuinfo <vm>
      • Replace overcloud-compute-n with the host name of the Compute node.
      • Replace <vm> with the name of the instance.
    • To view details about which NUMA node the instance is using, run the following command:

      $ ssh root@overcloud-compute-n
      # virsh numatune <vm>
      • Replace overcloud-compute-n with the host name of the Compute node.
      • Replace <vm> with the name or ID of the instance.

When you finish migrating the instances, proceed to Completing the migration.

5.7. Checking migration status

Migration involves several state transitions before migration is complete. During a healthy migration, the migration state typically transitions as follows:

  1. Queued: The Compute service has accepted the request to migrate an instance, and migration is pending.
  2. Preparing: The Compute service is preparing to migrate the instance.
  3. Running: The Compute service is migrating the instance.
  4. Post-migrating: The Compute service has built the instance on the destination Compute node and is releasing resources on the source Compute node.
  5. Completed: The Compute service has completed migrating the instance and finished releasing resources on the source Compute node.

Procedure

  1. Retrieve the list of migration IDs for the instance:

    $ nova server-migration-list <vm>
    
    +----+-------------+-----------  (...)
    | Id | Source Node | Dest Node | (...)
    +----+-------------+-----------+ (...)
    | 2  | -           | -         | (...)
    +----+-------------+-----------+ (...)

    Replace <vm> with the name or ID of the instance.

  2. Show the status of the migration:

    $  <vm> <migration-id>
    • Replace <vm> with the name or ID of the instance.
    • Replace <migration-id> with the ID of the migration.

      Running the nova server-migration-show command returns the following example output:

      +------------------------+--------------------------------------+
      | Property               | Value                                |
      +------------------------+--------------------------------------+
      | created_at             | 2017-03-08T02:53:06.000000           |
      | dest_compute           | controller                           |
      | dest_host              | -                                    |
      | dest_node              | -                                    |
      | disk_processed_bytes   | 0                                    |
      | disk_remaining_bytes   | 0                                    |
      | disk_total_bytes       | 0                                    |
      | id                     | 2                                    |
      | memory_processed_bytes | 65502513                             |
      | memory_remaining_bytes | 786427904                            |
      | memory_total_bytes     | 1091379200                           |
      | server_uuid            | d1df1b5a-70c4-4fed-98b7-423362f2c47c |
      | source_compute         | compute2                             |
      | source_node            | -                                    |
      | status                 | running                              |
      | updated_at             | 2017-03-08T02:53:47.000000           |
      +------------------------+--------------------------------------+
      Tip

      The OpenStack Compute service measures progress of the migration by the number of remaining memory bytes to copy. If this number does not decrease over time, the migration might be unable to complete, and the Compute service might abort it.

Sometimes instance migration can take a long time or encounter errors. For more information, see Section 5.10, “Troubleshooting migration”.

5.8. Completing the migration

After you migrate one or more instances, you need to re-enable the source Compute nodes from the undercloud to ensure that the scheduler can assign new instances to the source Compute node. For migrated instances that use DPDK, you must also re-enable the destination Compute node from the undercloud.

Procedure

  1. Re-enable the source Compute node:

    (overcloud) $ source ~/stackrc
    (undercloud) $ openstack compute service set <source> nova-compute --enable

    Replace <source> with the host name of the source Compute node.

  2. Optional: For instances that use DPDK, re-enable the destination Compute node from the undercloud:

    (undercloud) $ openstack compute service set <dest> nova-compute --enable

    Replace <dest> with the host name of the destination Compute node.

5.9. Evacuating an instance

If you want to move an instance from a dead or shut-down Compute node to a new host in the same environment, you can evacuate it. The evacuate process rebuilds the instance on another Compute node. If the instance uses shared storage, the instance root disk is not rebuilt during the evacuate process, as the disk remains accessible by the destination Compute node. If the instance does not use shared storage, then the instance root disk is also rebuilt on the destination Compute node.

Note
  • You can only perform an evacuation when the Compute node is fenced, and the API reports that the state of the Compute node is "down" or "forced-down". If the Compute node is not reported as "down" or "forced-down", the evacuate command fails.
  • To perform an evacuation, you must be a cloud administrator.

5.9.1. Evacuating one instance

You can evacuate instances one at a time.

Procedure

  1. Log onto the failed Compute node as an administrator.
  2. Disable the Compute node:

    (overcloud) [stack@director ~]$ openstack compute service set \
    <host> <service> --disable
    • Replace <host> with the name of the Compute node to evacuate the instance from.
    • Replace <service> with the name of the service to disable, for example nova-compute.
  3. To evacuate an instance, run the following command:

    (overcloud) [stack@director ~]$ nova evacuate [--password <pass>] <vm> [dest]
    • Replace <pass> with the admin password to set for the evacuated instance. If a password is not specified, a random password is generated and output when the evacuation is complete.
    • Replace <vm> with the name or ID of the instance to evacuate.
    • Replace [dest] with the name of the Compute node to evacuate the instance to. If you do not specify the destination Compute node, the Compute scheduler selects one for you. You can find possible Compute nodes by using the following command:

      (overcloud) [stack@director ~]$ openstack hypervisor list

5.9.2. Evacuating all instances on a host

You can evacuate all instances on a specified Compute node.

Procedure

  1. Log onto the failed Compute node as an administrator.
  2. Disable the Compute node:

    (overcloud) [stack@director ~]$ openstack compute service set \
    <host> <service> --disable
    • Replace <host> with the name of the Compute node to evacuate the instances from.
    • Replace <service> with the name of the service to disable, for example nova-compute.
  3. Evacuate all instances on a specified Compute node:

    (overcloud) [stack@director ~]$ nova host-evacuate [--target_host <dest>] [--force] <host>
    • Replace <dest> with the name of the destination Compute node to evacuate the instances to. If you do not specify the destination, the Compute scheduler selects one for you. You can find possible Compute nodes by using the following command:

      (overcloud) [stack@director ~]$ openstack hypervisor list
    • Replace <host> with the name of the Compute node to evacuate the instances from.

5.9.3. Configuring shared storage

If you are using shared storage, export the instance directory for the Compute service to the two nodes, and ensure that the nodes have access. The directory path is set in the state_path and instances_path parameters in your Compute environment file. This procedure uses the default value, which is /var/lib/nova/instances. Only users with root access can set up shared storage. The Compute service user in the following procedure must be the same across Controller and Compute nodes.

Procedure

  1. Perform the following steps on the Controller node:

    1. Ensure that the /var/lib/nova/instances directory has read-write access by the Compute service user, as shown in the following example:

      drwxr-xr-x.  9 nova nova 4096 Nov  5 20:37 instances
    2. Add the following lines to the /etc/exports file:

      /var/lib/nova/instances node1_IP(rw,sync,fsid=0,no_root_squash)
      /var/lib/nova/instances node2_IP(rw,sync,fsid=0,no_root_squash)

      Replace node1_IP and node2_IP for the IP addresses of the two Compute nodes, for example:

      /var/lib/nova/instances 192.168.24.9(rw,sync,fsid=0,no_root_squash)
      /var/lib/nova/instances 192.168.24.21(rw,sync,fsid=0,no_root_squash)
    3. Export the /var/lib/nova/instances directory to the Compute nodes:

      # exportfs -avr
    4. Restart the NFS server:

      # systemctl restart nfs-server
  2. Perform the following steps on each Compute node:

    1. Ensure that the /var/lib/nova/instances directory exists locally.
    2. Add the following line to the /etc/fstab file:

      NFS_SHARE_PATH:/var/lib/nova/instances /var/lib/nova/instances nfs4 defaults 0 0
    3. Mount the controller’s instance directory to mount all the devices listed in /etc/fstab:

      # mount -a -v
    4. Ensure that QEMU can access the directory’s images:

      # ls -ld /var/lib/nova/instances
      drwxr-xr-x. 9 nova nova 4096 Nov  5 20:37 /var/lib/nova/instances
    5. Ensure that the node can see the instances directory with:

      drwxr-xr-x. 9 nova nova 4096 Nov  5 20:37 /var/lib/nova/instances
Note

You can also run the following to view all mounted devices:

# df -k

5.10. Troubleshooting migration

The following issues can arise during instance migration:

  • The migration process encounters errors.
  • The migration process never ends.
  • Performance of the instance degrades after migration.

5.10.1. Errors during migration

The following issues can send the migration operation into an error state:

  • Running a cluster with different versions of Red Hat OpenStack Platform (RHOSP).
  • Specifying an instance ID that cannot be found.
  • The instance you are trying to migrate is in an error state.
  • The Compute service is shutting down.
  • A race condition occurs.
  • Live migration enters a failed state.

When live migration enters a failed state, it is typically followed by an error state. The following common issues can cause a failed state:

  • A destination Compute host is not available.
  • A scheduler exception occurs.
  • The rebuild process fails due to insufficient computing resources.
  • A server group check fails.
  • The instance on the source Compute node gets deleted before migration to the destination Compute node is complete.

5.10.2. Never-ending live migration

Live migration can fail to complete, which leaves migration in a perpetual running state. A common reason for a live migration that never completes is that client requests to the instance running on the source Compute node create changes that occur faster than the Compute service can replicate them to the destination Compute node.

Use one of the following methods to address this situation:

  • Abort the live migration.
  • Force the live migration to complete.

Aborting live migration

If the instance state changes faster than the migration procedure can copy it to the destination node, and you do not want to temporarily suspend the instance operations, you can abort the live migration.

Procedure

  1. Retrieve the list of migrations for the instance:

    $ nova server-migration-list <vm>

    Replace <vm> with the name or ID of the instance.

  2. Abort the live migration:

    $ nova live-migration-abort <vm> <migration-id>
    • Replace <vm> with the name or ID of the instance.
    • Replace <migration-id> with the ID of the migration.

Forcing live migration to complete

If the instance state changes faster than the migration procedure can copy it to the destination node, and you want to temporarily suspend the instance operations to force migration to complete, you can force the live migration procedure to complete.

Important

Forcing live migration to complete might lead to perceptible downtime.

Procedure

  1. Retrieve the list of migrations for the instance:

    $ nova server-migration-list <vm>

    Replace <vm> with the name or ID of the instance.

  2. Force the live migration to complete:

    $ nova live-migration-force-complete <vm> <migration-id>
    • Replace <vm> with the name or ID of the instance.
    • Replace <migration-id> with the ID of the migration.

5.10.3. Instance performance degrades after migration

For instances that use a NUMA topology, the source and destination Compute nodes must have the same NUMA topology and configuration. The NUMA topology of the destination Compute node must have sufficient resources available. If the NUMA configuration between the source and destination Compute nodes is not the same, it is possible that live migration succeeds while the instance performance degrades. For example, if the source Compute node maps NIC 1 to NUMA node 0, but the destination Compute node maps NIC 1 to NUMA node 5, after migration the instance might route network traffic from a first CPU across the bus to a second CPU with NUMA node 5 to route traffic to NIC 1. This can result in expected behavior, but degraded performance. Similarly, if NUMA node 0 on the source Compute node has sufficient available CPU and RAM, but NUMA node 0 on the destination Compute node already has instances using some of the resources, the instance might run correctly but suffer performance degradation. For more information, see Section 5.2, “Migration constraints”.

Chapter 6. Configuring Compute nodes for performance

You can configure the scheduling and placement of instances for optimal performance by creating customized flavors to target specialized workloads, including NFV and High Performance Computing (HPC).

Use the following features to tune your instances for optimal performance:

  • CPU pinning: Pin virtual CPUs to physical CPUs.
  • Emulator threads: Pin emulator threads associated with the instance to physical CPUs.
  • Huge pages: Tune instance memory allocation policies both for normal memory (4k pages) and huge pages (2 MB or 1 GB pages).
Note

Configuring any of these features creates an implicit NUMA topology on the instance if there is no NUMA topology already present.

6.1. Configuring CPU pinning with NUMA

This chapter describes how to use NUMA topology awareness to configure an OpenStack environment on systems with a NUMA architecture. The procedures detailed in this chapter show you how to pin virtual machines (VMs) to dedicated CPU cores, which improves scheduling and VM performance.

Tip

Background information about NUMA is available in the following article: What is NUMA and how does it work on Linux?

The following diagram provides an example of a two-node NUMA system and the way the CPU cores and memory pages are made available:

OpenStack NUMA Topology 39825 0416 ADF
Note

Remote memory available via Interconnect is accessed only if VM1 from NUMA node 0 has a CPU core in NUMA node 1. In this case, the memory of NUMA node 1 will act as local for the third CPU core of VM1 (for example, if VM1 is allocated with CPU 4 in the diagram above), but at the same time, it will act as remote memory for the other CPU cores of the same VM.

For more details on NUMA tuning with libvirt, see the Virtualization Tuning and Optimization Guide.

6.1.1. Compute node configuration

The exact configuration depends on the NUMA topology of your host system. However, you must reserve some CPU cores across all the NUMA nodes for host processes and let the rest of the CPU cores handle your virtual machines (VMs). The following example illustrates the layout of eight CPU cores evenly spread across two NUMA nodes.

Table 6.1. Example of NUMA Topology

 

Node 0

Node 1

Host processes

Core 0

Core 1

Core 4

Core 5

VMs

Core 2

Core 3

Core 6

Core 7

Note

Determine the number of cores to reserve for host processes by observing the performance of the host under typical workloads.

Procedure

  1. Reserve CPU cores for the VMs by setting the NovaVcpuPinSet configuration in the Compute environment file:

    NovaVcpuPinSet: 2,3,6,7
  2. Set the NovaReservedHostMemory option in the same file to the amount of RAM to reserve for host processes. For example, if you want to reserve 512 MB, use:

    NovaReservedHostMemory: 512
  3. To ensure that host processes do not run on the CPU cores reserved for VMs, set the parameter IsolCpusList in the Compute environment file to the CPU cores you have reserved for VMs. Specify the value of the IsolCpusList parameter using a list of CPU indices, or ranges separated by a whitespace. For example:

    IsolCpusList: 2 3 6 7
    Note

    The IsolCpusList parameter ensures that the underlying compute node is not able to use the corresponding pCPUs for itself. The pCPUs are dedicated to the VMs.

  4. To apply this configuration, deploy the overcloud:

    (undercloud) $ openstack overcloud deploy --templates \
      -e /home/stack/templates/<compute_environment_file>.yaml

6.1.2. Scheduler configuration

Procedure

  1. Open your Compute environment file.
  2. Add the following values to the NovaSchedulerDefaultFilters parameter, if they are not already present:

    • NUMATopologyFilter
    • AggregateInstanceExtraSpecsFilter
  3. Save the configuration file.
  4. Deploy the overcloud.

6.1.3. Aggregate and flavor configuration

Configure host aggregates to deploy instances that use CPU pinning on different hosts from instances that do not, to avoid unpinned instances using the resourcing requirements of pinned instances.

Caution

Do not deploy instances with NUMA topology on the same hosts as instances that do not have NUMA topology.

Prepare your OpenStack environment for running virtual machine instances pinned to specific resources by completing the following steps on a system with the Compute CLI.

Procedure

  1. Load the admin credentials:

    source ~/keystonerc_admin
  2. Create an aggregate for the hosts that will receive pinning requests:

    nova aggregate-create <aggregate-name-pinned>
  3. Enable the pinning by editing the metadata for the aggregate:

    nova aggregate-set-metadata <aggregate-pinned-UUID> pinned=true
  4. Create an aggregate for other hosts:

    nova aggregate-create <aggregate-name-unpinned>
  5. Edit the metadata for this aggregate accordingly:

    nova aggregate-set-metadata <aggregate-unpinned-UUID> pinned=false
  6. Change your existing flavors' specifications to this one:

    for i in $(nova flavor-list | cut -f 2 -d ' ' | grep -o '[0-9]*'); do nova flavor-key $i set "aggregate_instance_extra_specs:pinned"="false"; done
  7. Create a flavor for the hosts that will receive pinning requests:

    nova flavor-create <flavor-name-pinned> <flavor-ID> <RAM> <disk-size> <vCPUs>

    Where:

    • <flavor-ID> - Set to auto if you want nova to generate a UUID.
    • <RAM> - Specify the required RAM in MB.
    • <disk-size> - Specify the required disk size in GB.
    • <vCPUs> - The number of virtual CPUs that you want to reserve.
  8. Set the hw:cpu_policy specification of this flavor to dedicated so as to require dedicated resources, which enables CPU pinning, and also the hw:cpu_thread_policy specification to require, which places each vCPU on thread siblings:

    nova flavor-key <flavor-name-pinned> set hw:cpu_policy=dedicated
    nova flavor-key <flavor-name-pinned> set hw:cpu_thread_policy=require
    Note

    If the host does not have an SMT architecture or enough CPU cores with free thread siblings, scheduling will fail. If such behavior is undesired, or if your hosts simply do not have an SMT architecture, do not use the hw:cpu_thread_policy specification, or set it to prefer instead of require. The (default) prefer policy ensures that thread siblings are used when available.

  9. Set the aggregate_instance_extra_specs:pinned specification to "true" to ensure that instances based on this flavor have this specification in their aggregate metadata:

    nova flavor-key <flavor-name-pinned> set aggregate_instance_extra_specs:pinned=true
  10. Add some hosts to the new aggregates:

    nova aggregate-add-host <aggregate-pinned-UUID> <host_name>
    nova aggregate-add-host <aggregate-unpinned-UUID> <host_name>
  11. Boot an instance using the new flavor:

    nova boot --image <image-name> --flavor <flavor-name-pinned> <server-name>
  12. To verify that the new server has been placed correctly, run the following command and check for OS-EXT-SRV-ATTR:hypervisor_hostname in the output:

    nova show <server-name>

6.2. Configuring huge pages on the Compute node

Configure the Compute node to enable instances to request huge pages.

Procedure

  1. Configure the amount of huge page memory to reserve on each NUMA node for processes that are not instances:

    parameter_defaults:
      NovaReservedHugePages: ["node:0,size:2048,count:64","node:1,size:1GB,count:1"]

    Where:

    Attribute

    Description

    size

    The size of the allocated huge page. Valid values: * 2048 (for 2MB) * 1GB

    count

    The number of huge pages used by OVS per NUMA node. For example, for 4096 of socket memory used by Open vSwitch, set this to 2.

  2. (Optional) To allow instances to allocate 1GB huge pages, configure the CPU feature flags, cpu_model_extra_flags, to include "pdpe1gb":

    parameter_defaults:
       ComputeExtraConfig:
         nova::compute::libvirt::libvirt_cpu_mode: 'custom'
         nova::compute::libvirt::libvirt_cpu_model: 'Haswell-noTSX'
         nova::compute::libvirt::libvirt_cpu_model_extra_flags: 'vmx, pdpe1gb'
    Note
    • CPU feature flags do not need to be configured to allow instances to only request 2 MB huge pages.
    • You can only allocate 1G huge pages to an instance if the host supports 1G huge page allocation.
    • You only need to set cpu_model_extra_flags to pdpe1gb when cpu_mode is set to host-model or custom.
    • If the host supports pdpe1gb, and host-passthrough is used as the cpu_mode, then you do not need to set pdpe1gb as a cpu_model_extra_flags. The pdpe1gb flag is only included in Opteron_G4 and Opteron_G5 CPU models, it is not included in any of the Intel CPU models supported by QEMU.
    • To mitigate for CPU hardware issues, such as Microarchitectural Data Sampling (MDS), you might need to configure other CPU flags. For more information, see RHOS Mitigation for MDS ("Microarchitectural Data Sampling") Security Flaws.
  3. To avoid loss of performance after applying Meltdown protection, configure the CPU feature flags, cpu_model_extra_flags, to include "+pcid":

    parameter_defaults:
       ComputeExtraConfig:
         nova::compute::libvirt::libvirt_cpu_mode: 'custom'
         nova::compute::libvirt::libvirt_cpu_model: 'Haswell-noTSX'
         nova::compute::libvirt::libvirt_cpu_model_extra_flags: 'vmx, pdpe1gb, +pcid'
  4. Add NUMATopologyFilter to the NovaSchedulerDefaultFilters parameter in each Compute environment file, if not already present.
  5. Apply this huge page configuration by adding the environment file(s) to your deployment command and deploying the overcloud:

    (undercloud) $ openstack overcloud deploy --templates \
      -e [your environment files]
      -e /home/stack/templates/<compute_environment_file>.yaml

6.2.1. Allocating huge pages to instances

Create a flavor with the hw:mem_page_size extra specification key to specify that the instance should use huge pages.

Prerequisites

Procedure

  1. Create a flavor for instances that require huge pages:

    $ openstack flavor create --ram <size-mb> --disk <size-gb> --vcpus <no_reserved_vcpus> huge_pages
  2. Set the flavor for huge pages:

    $ openstack flavor set huge_pages --property hw:mem_page_size=1GB

    Valid values for hw:mem_page_size:

    • large - Selects the largest page size supported on the host, which may be 2 MB or 1 GB on x86_64 systems.
    • small - (Default) Selects the smallest page size supported on the host. On x86_64 systems this is 4 kB (normal pages).
    • any - Selects the largest available huge page size, as determined by the libvirt driver.
    • <pagesize>: (string) Set an explicit page size if the workload has specific requirements. Use an integer value for the page size in KB, or any standard suffix. For example: 4KB, 2MB, 2048, 1GB.
  3. Create an instance using the new flavor:

    $ openstack server create --flavor huge_pages --image <image> huge_pages_instance

Validation

The scheduler identifies a host with enough free huge pages of the required size to back the memory of the instance. If the scheduler is unable to find a host and NUMA node with enough pages, then the request will fail with a NoValidHost error.

Chapter 7. Configuring Real-Time Compute

In some use-cases, you might need instances on your Compute nodes to adhere to low-latency policies and perform real-time processing. Real-time Compute nodes include a real-time capable kernel, specific virtualization modules, and optimized deployment parameters, to facilitate real-time processing requirements and minimize latency.

The process to enable Real-time Compute includes:

  • configuring the BIOS settings of the Compute nodes
  • building a real-time image with real-time kernel and Real-Time KVM (RT-KVM) kernel module
  • assigning the ComputeRealTime role to the Compute nodes

For a use-case example of Real-time Compute deployment for NFV workloads, see the Example: Configuring OVS-DPDK with ODL and VXLAN tunnelling section in the Network Functions Virtualization Planning and Configuration Guide.

7.1. Preparing Your Compute Nodes for Real-Time

Note

Real-time Compute nodes are supported only with Red Hat Enterprise Linux version 7.5 or later.

Before you can deploy Real-time Compute in your overcloud, you must enable Red Hat Enterprise Linux Real-Time KVM (RT-KVM), configure your BIOS to support real-time, and build the real-time image.

Prerequisites

  • You must use Red Hat certified servers for your RT-KVM Compute nodes. See Red Hat Enterprise Linux for Real Time 7 certified servers for details.
  • You must enable the rhel-7-server-nfv-rpms repository for RT-KVM to build the real-time image.

    Note

    You need a separate subscription to Red Hat OpenStack Platform for Real Time before you can access this repository. For details on managing repositories and subscriptions for your undercloud, see the Registering and updating your undercloud section in the Director Installation and Usage guide.

    To check which packages will be installed from the repository, run the following command:

    $ yum repo-pkgs rhel-7-server-nfv-rpms list
    Loaded plugins: product-id, search-disabled-repos, subscription-manager
    Available Packages
    kernel-rt.x86_64                                                                     3.10.0-693.21.1.rt56.639.el7                                                       rhel-7-server-nfv-rpms
    kernel-rt-debug.x86_64                                                               3.10.0-693.21.1.rt56.639.el7                                                       rhel-7-server-nfv-rpms
    kernel-rt-debug-devel.x86_64                                                         3.10.0-693.21.1.rt56.639.el7                                                       rhel-7-server-nfv-rpms
    kernel-rt-debug-kvm.x86_64                                                           3.10.0-693.21.1.rt56.639.el7                                                       rhel-7-server-nfv-rpms
    kernel-rt-devel.x86_64                                                               3.10.0-693.21.1.rt56.639.el7                                                       rhel-7-server-nfv-rpms
    kernel-rt-doc.noarch                                                                 3.10.0-693.21.1.rt56.639.el7                                                       rhel-7-server-nfv-rpms
    kernel-rt-kvm.x86_64                                                                 3.10.0-693.21.1.rt56.639.el7                                                       rhel-7-server-nfv-rpms
    [ output omitted…]

Building the real-time image

To build the overcloud image for Real-time Compute nodes:

  1. Install the libguestfs-tools package on the undercloud to get the virt-customize tool:

    (undercloud) [stack@undercloud-0 ~]$ sudo yum install libguestfs-tools
  2. Extract the images:

    (undercloud) [stack@undercloud-0 ~]$ tar -xf /usr/share/rhosp-director-images/overcloud-full.tar
    (undercloud) [stack@undercloud-0 ~]$ tar -xf /usr/share/rhosp-director-images/ironic-python-agent.tar
  3. Copy the default image:

    (undercloud) [stack@undercloud-0 ~]$ cp overcloud-full.qcow2 overcloud-realtime-compute.qcow2
  4. Register the image and configure the required subscriptions:

    (undercloud) [stack@undercloud-0 ~]$  virt-customize -a overcloud-realtime-compute.qcow2 --run-command 'subscription-manager register --username=[username] --password=[password]'
    [  0.0] Examining the guest ...
    [ 10.0] Setting a random seed
    [ 10.0] Running: subscription-manager register --username=[username] --password=[password]
    [ 24.0] Finishing off

    Replace the username and password values with your Red Hat customer account details. For general information about building a Real-time overcloud image, see the Modifying the Red Hat Enterprise Linux OpenStack Platform Overcloud Image with virt-customize knowledgebase article.

  5. Find the SKU of the Red Hat OpenStack Platform for Real Time subscription. The SKU might be located on a system that is already registered to the Red Hat Subscription Manager with the same account and credentials. For example:

    $ sudo subscription-manager list
  6. Attach the Red Hat OpenStack Platform for Real Time subscription to the image:

    (undercloud) [stack@undercloud-0 ~]$  virt-customize -a overcloud-realtime-compute.qcow2 --run-command 'subscription-manager attach --pool [subscription-pool]'
  7. Create a script to configure rt on the image:

    (undercloud) [stack@undercloud-0 ~]$ cat rt.sh
      #!/bin/bash
    
      set -eux
    
      subscription-manager repos --enable=rhel-7-server-rpms --enable=rhel-7-server-openstack-13-rpms --enable=rhel-7-server-nfv-rpms
      yum -v -y --setopt=protected_packages= erase kernel.$(uname -m)
      yum -v -y install kernel-rt kernel-rt-kvm tuned-profiles-nfv-host
    
      # END OF SCRIPT
  8. Run the script to configure the real-time image:

    (undercloud) [stack@undercloud-0 ~]$ virt-customize -a overcloud-realtime-compute.qcow2 -v --run rt.sh 2>&1 | tee virt-customize.log
  9. Re-label SELinux:

    (undercloud) [stack@undercloud-0 ~]$ virt-customize -a overcloud-realtime-compute.qcow2 --selinux-relabel
  10. Extract vmlinuz and initrd:

    (undercloud) [stack@undercloud-0 ~]$ mkdir image
    (undercloud) [stack@undercloud-0 ~]$ guestmount -a overcloud-realtime-compute.qcow2 -i --ro image
    (undercloud) [stack@undercloud-0 ~]$ cp image/boot/vmlinuz-3.10.0-862.rt56.804.el7.x86_64 ./overcloud-realtime-compute.vmlinuz
    (undercloud) [stack@undercloud-0 ~]$ cp image/boot/initramfs-3.10.0-862.rt56.804.el7.x86_64.img ./overcloud-realtime-compute.initrd
    (undercloud) [stack@undercloud-0 ~]$ guestunmount image
    Note

    The software version in the vmlinuz and initramfs filenames vary with the kernel version.

  11. Upload the image:

    (undercloud) [stack@undercloud-0 ~]$ openstack overcloud image upload --update-existing --os-image-name overcloud-realtime-compute.qcow2

You now have a real-time image you can use with the ComputeRealTime composable role on select Compute nodes.

Modifying BIOS settings on Real-time Compute nodes

To reduce latency on your Real-time Compute nodes, you must modify the BIOS settings in the Compute nodes. You should disable all options for the following components in your Compute node BIOS settings:

  • Power Management
  • Hyper-Threading
  • CPU sleep states
  • Logical processors

See Setting BIOS parameters for descriptions of these settings and the impact of disabling them. See your hardware manufacturer documentation for complete details on how to change BIOS settings.

7.2. Deploying the Real-time Compute Role

Red Hat OpenStack Platform Director provides the template for the ComputeRealTime role, which you can then use to deploy Real-time Compute nodes. However, you must perform additional steps to designate Compute nodes for real-time.

  1. Based on the /usr/share/openstack-tripleo-heat-templates/environments/compute-real-time-example.yaml file, create a compute-real-time.yaml environment file that sets the parameters for the ComputeRealTime role.

    cp /usr/share/openstack-tripleo-heat-templates/environments/compute-real-time-example.yaml /home/stack/templates/compute-real-time.yaml

    The file must include values for the following parameters:

    • IsolCpusList and NovaVcpuPinSet. List of isolated CPU cores and virtual CPU pins to reserve for real-time workloads. This value depends on the CPU hardware of your Real-time Compute nodes.
    • KernelArgs. Arguments to pass to the kernel of the Real-time Compute nodes. For example, you can use default_hugepagesz=1G hugepagesz=1G hugepages=<number_of_1G_pages_to_reserve> hugepagesz=2M hugepages=<number_of_2M_pages> to define the memory requirements of guests that have huge pages with multiple sizes. In this example, the default size is 1GB but you can also reserve 2M huge pages.
  2. Add the ComputeRealTime role to your roles data file and regenerate the file. For example:

    $ openstack overcloud roles generate -o /home/stack/templates/rt_roles_data.yaml Controller Compute ComputeRealTime

    This command generates a ComputeRealTime role with contents similar to the following example, and also sets the ImageDefault option to overcloud-realtime-compute.

    ###############################################################
    # Role: ComputeRealTime                                                               #
    ###############################################################
    
    - name: ComputeRealTime
      description: |
        Compute role that is optimized for real-time behaviour. When using this role
        it is mandatory that an overcloud-realtime-compute image is available and
        the role specific parameters IsolCpusList and NovaVcpuPinSet are set
        accordingly to the hardware of the real-time compute nodes.
      CountDefault: 1
      networks:
        - InternalApi
        - Tenant
        - Storage
      HostnameFormatDefault: '%stackname%-computerealtime-%index%'
      disable_upgrade_deployment: True
      ImageDefault: overcloud-realtime-compute
      RoleParametersDefault:
        TunedProfileName: "realtime-virtual-host"
        KernelArgs: ""      # these must be set in an environment file or similar
        IsolCpusList: ""    # according to the hardware of real-time nodes
        NovaVcpuPinSet: ""  #
      ServicesDefault:
        - OS::TripleO::Services::Aide
        - OS::TripleO::Services::AuditD
        - OS::TripleO::Services::CACerts
        - OS::TripleO::Services::CephClient
        - OS::TripleO::Services::CephExternal
        - OS::TripleO::Services::CertmongerUser
        - OS::TripleO::Services::Collectd
        - OS::TripleO::Services::ComputeCeilometerAgent
        - OS::TripleO::Services::ComputeNeutronCorePlugin
        - OS::TripleO::Services::ComputeNeutronL3Agent
        - OS::TripleO::Services::ComputeNeutronMetadataAgent
        - OS::TripleO::Services::ComputeNeutronOvsAgent
        - OS::TripleO::Services::Docker
        - OS::TripleO::Services::Fluentd
        - OS::TripleO::Services::Ipsec
        - OS::TripleO::Services::Iscsid
        - OS::TripleO::Services::Kernel
        - OS::TripleO::Services::LoginDefs
        - OS::TripleO::Services::MySQLClient
        - OS::TripleO::Services::NeutronBgpVpnBagpipe
        - OS::TripleO::Services::NeutronLinuxbridgeAgent
        - OS::TripleO::Services::NeutronVppAgent
        - OS::TripleO::Services::NovaCompute
        - OS::TripleO::Services::NovaLibvirt
        - OS::TripleO::Services::NovaMigrationTarget
        - OS::TripleO::Services::Ntp
        - OS::TripleO::Services::ContainersLogrotateCrond
        - OS::TripleO::Services::OpenDaylightOvs
        - OS::TripleO::Services::Rhsm
        - OS::TripleO::Services::RsyslogSidecar
        - OS::TripleO::Services::Securetty
        - OS::TripleO::Services::SensuClient
        - OS::TripleO::Services::SkydiveAgent
        - OS::TripleO::Services::Snmp
        - OS::TripleO::Services::Sshd
        - OS::TripleO::Services::Timezone
        - OS::TripleO::Services::TripleoFirewall
        - OS::TripleO::Services::TripleoPackages
        - OS::TripleO::Services::Vpp
        - OS::TripleO::Services::OVNController
        - OS::TripleO::Services::OVNMetadataAgent
        - OS::TripleO::Services::Ptp

    For general information about custom roles and about the roles-data.yaml, see the Roles section.

  3. Create the compute-realtime flavor to tag nodes that you want to designate for real-time workloads. For example:

    $ source ~/stackrc
    $ openstack flavor create --id auto --ram 6144 --disk 40 --vcpus 4 compute-realtime
    $ openstack flavor set --property "cpu_arch"="x86_64" --property "capabilities:boot_option"="local" --property "capabilities:profile"="compute-realtime" compute-realtime
  4. Tag each node that you want to designate for real-time workloads with the compute-realtime profile.

    $ openstack baremetal node set --property capabilities='profile:compute-realtime,boot_option:local' <NODE UUID>
  5. Map the ComputeRealTime role to the compute-realtime flavor by creating an environment file with the following content:

    parameter_defaults:
      OvercloudComputeRealTimeFlavor: compute-realtime
  6. Run the openstack overcloud deploy command with the -e option and specify all the environment files that you created, as well as the new roles file. For example:

    $ openstack overcloud deploy -r /home/stack/templates/rt~/my_roles_data.yaml  -e /home/stack/templates/compute-real-time.yaml <FLAVOR_ENV_FILE>
    Note

    If you want to run additional real-time instances on the same Compute node, you can change the priority of the instances in the realtime_schedule_priority paremeter in the nova.conf file.

7.3. Sample Deployment and Testing Scenario

The following example procedure uses a simple single-node deployment to test that the environment variables and other supporting configuration is set up correctly. Actual performance results might vary, depending on the number of nodes and guests that you deploy in your cloud.

  1. Create the compute-real-time.yaml file with the following parameters:

    parameter_defaults:
      ComputeRealTimeParameters:
        IsolCpusList: "1"
        NovaVcpuPinSet: "1"
        KernelArgs: "default_hugepagesz=1G hugepagesz=1G hugepages=16"
  2. Create a new rt_roles_data.yaml file with the ComputeRealTime role.

    $ openstack overcloud roles generate -o ~/rt_roles_data.yaml Controller ComputeRealTime
  3. Deploy the overcloud, adding both your new real-time roles data file and your real-time environment file to the stack along with your other environment files:

    (undercloud) $ openstack overcloud deploy --templates \
      -r /home/stack/rt_roles_data.yaml
      -e [your environment files]
      -e /home/stack/templates/compute-real-time.yaml

    This command deploys one Controller node and one Real-time Compute node.

  4. Log into the Real-time Compute node and check the following parameters. Replace <...> with the values of the relevant parameters from the compute-real-time.yaml.

    [root@overcloud-computerealtime-0 ~]# uname -a
    Linux overcloud-computerealtime-0 3.10.0-693.11.1.rt56.632.el7.x86_64 #1 SMP PREEMPT RT Wed Dec 13 13:37:53 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
    [root@overcloud-computerealtime-0 ~]# cat /proc/cmdline
    BOOT_IMAGE=/boot/vmlinuz-3.10.0-693.11.1.rt56.632.el7.x86_64 root=UUID=45ae42d0-58e7-44fe-b5b1-993fe97b760f ro console=tty0 crashkernel=auto console=ttyS0,115200 default_hugepagesz=1G hugepagesz=1G hugepages=16
    [root@overcloud-computerealtime-0 ~]# tuned-adm active
    Current active profile: realtime-virtual-host
    [root@overcloud-computerealtime-0 ~]# grep ^isolated_cores /etc/tuned/realtime-virtual-host-variables.conf
    isolated_cores=<IsolCpusList>
    [root@overcloud-computerealtime-0 ~]# cat /usr/lib/tuned/realtime-virtual-host/lapic_timer_adv_ns
    X (X != 0)
    [root@overcloud-computerealtime-0 ~]# cat /sys/module/kvm/parameters/lapic_timer_advance_ns
    X (X != 0)
    [root@overcloud-computerealtime-0 ~]# cat /sys/devices/system/node/node0/hugepages/hugepages-1048576kB/nr_hugepages
    X (X != 0)
    [root@overcloud-computerealtime-0 ~]# grep ^vcpu_pin_set /var/lib/config-data/puppet-generated/nova_libvirt/etc/nova/nova.conf
    vcpu_pin_set=<NovaVcpuPinSet>

7.4. Launching and Tuning Real-Time Instances

After you deploy and configure Real-time Compute nodes, you can launch real-time instances on those nodes. You can further configure these real-time instances with CPU pinning, NUMA topologies, and huge pages.

Configuring a real-time policy for instances

A real-time policy prioritizes real-time instances and minimizes latency during peak workload times. To set this policy, add the following parameters to the compute-realtime flavor.

$ openstack flavor set compute-realtime \
  --property hw:cpu_realtime=yes
  --property hw:cpu_realtime_mask=^0

Launching a real-time instance

  1. Make sure that the compute-realtime flavor exists on the overcloud, as described in the Deploying the Real-time Compute Role section.
  2. Launch the real-time instance.

    # openstack server create  --image <rhel> --flavor r1.small --nic net-id=<dpdk-net> test-rt
  3. If you have administrator access to the Compute host, you can optionally verify that the instance uses the assigned emulator threads.

    # virsh dumpxml <instance-id> | grep vcpu -A1
    <vcpu placement='static'>4</vcpu>
    <cputune>
      <vcpupin vcpu='0' cpuset='1'/>
      <vcpupin vcpu='1' cpuset='3'/>
      <vcpupin vcpu='2' cpuset='5'/>
      <vcpupin vcpu='3' cpuset='7'/>
      <emulatorpin cpuset='0-1'/>
      <vcpusched vcpus='2-3' scheduler='fifo'
      priority='1'/>
    </cputune>

Pinning CPUs and setting emulator thread policy

To ensure that there are enough CPUs on each Real-time Compute node for real-time workloads, you need to pin at least one virtual CPU (vCPU) for an instance to a physical CPU (pCPUs) on the host. The emulator threads for that vCPU then remain dedicated to that pCPU.

  1. Set the emulator_thread_policy parameter to isolate. For example:
# openstack flavor set --property hw:emulator_threads_policy=isolate
  1. Configure your flavor to use a dedicated CPU policy. To do so, set the hw:cpu_policy parameter to dedicated on the flavor. For example:
# openstack flavor set --property hw:cpu_policy=dedicated 99
Note

Make sure that your resources quota has enough pCPUs for the Real-time Compute nodes to consume.

For general information about CPU pinning, see the CPU Pinning chapter.

Optimizing your network configuration

Depending on the needs of your deployment, you might need to set parameters in the network-environment.yaml file to tune your network for certain real-time workloads.

To review an example configuration optimized for OVS-DPDK, see the Configuring OVS-DPDK with RT-KVM section of the Network Functions Virtualization Planning and Configuration Guide.

Configuring huge pages

It is recommended to set the default huge pages size to 1GB. Otherwise, TLB flushes might create jitter in the vCPU execution.

To set the huge pages size for the compute-realtime flavor, run the following command:

openstack flavor set compute-realtime --property hw:mem_page_size=large

For general information about using huge pages, see the Running DPDK applications web page.

Chapter 8. Configuring virtual GPUs for instances

To support GPU-based rendering on your instances, you can define and manage virtual GPU (vGPU) resources according to your available physical GPU devices and your hypervisor type. You can use this configuration to divide the rendering workloads between all your physical GPU devices more effectively, and to have more control over scheduling your vGPU-enabled instances.

To enable vGPU in OpenStack Compute, create flavors that your cloud users can use to create Red Hat Enterprise Linux (RHEL) instances with vGPU devices. Each instance can then support GPU workloads with virtual GPU devices that correspond to the physical GPU devices.

The OpenStack Compute service tracks the number of vGPU devices that are available for each GPU profile you define on each host. The Compute service schedules instances to these hosts based on the flavor, attaches the devices, and monitors usage on an ongoing basis. When an instance is deleted, the Compute service adds the vGPU devices back to the available pool.

8.1. Supported configurations and limitations

Supported GPU cards

For a list of supported NVIDIA GPU cards, see Virtual GPU Software Supported Products on the NVIDIA website.

Limitations when using vGPU devices

  • You can enable only one vGPU type on each Compute node.
  • Each instance can use only one vGPU resource.
  • Live migration of vGPU between hosts is not supported.
  • Suspend operations on a vGPU-enabled instance is not supported due to a libvirt limitation. Instead, you can snapshot or shelve the instance.
  • Resize and cold migration operations on an instance with a vGPU flavor does not automatically re-allocate the vGPU resources to the instance. After you resize or migrate the instance, you must rebuild it manually to re-allocate the vGPU resources.
  • By default, vGPU types on Compute hosts are not exposed to API users. To grant access, add the hosts to a host aggregate. For more information, see Section 4.4, “Managing host aggregates”.
  • If you use NVIDIA accelerator hardware, you must comply with the NVIDIA licensing requirements. For example, NVIDIA vGPU GRID requires a licensing server. For more information about the NVIDIA licensing requirements, see NVIDIA License Server Release Notes on the NVIDIA website.

8.2. Configuring vGPU on the Compute nodes

To enable your cloud users to create instances that use a virtual GPU (vGPU), you must configure the Compute nodes that have the physical GPUs:

  1. Build a custom GPU-enabled overcloud image.
  2. Prepare the GPU role, profile, and flavor for designating Compute nodes for vGPU.
  3. Configure the Compute node for vGPU.
  4. Deploy the overcloud.
Note

To use an NVIDIA GRID vGPU, you must comply with the NVIDIA GRID licensing requirements and you must have the URL of your self-hosted license server. For more information, see the NVIDIA License Server Release Notes web page.

8.2.1. Building a custom GPU overcloud image

Perform the following steps on the director node to install the NVIDIA GRID host driver on an overcloud Compute image and upload the image to the OpenStack Image Service (glance).

Procedure

  1. Copy the overcloud image and add the gpu suffix to the copied image.

    $ cp overcloud-full.qcow2 overcloud-full-gpu.qcow2
  2. Install an ISO image generator tool from YUM.

    $ sudo yum install genisoimage -y
  3. Download the NVIDIA GRID host driver RPM package that corresponds to your GPU device from the NVIDIA website. To determine which driver you need, see the NVIDIA Driver Downloads Portal.

    Note

    You must be a registered NVIDIA customer to download the drivers from the portal.

  4. Create an ISO image from the driver RPM package and save the image in the nvidia-host directory.

    $ genisoimage -o nvidia-host.iso -R -J -V NVIDIA nvidia-host/
    I: -input-charset not specified, using utf-8 (detected in locale settings)
      9.06% done, estimate finish Wed Oct 31 11:24:46 2018
     18.08% done, estimate finish Wed Oct 31 11:24:46 2018
     27.14% done, estimate finish Wed Oct 31 11:24:46 2018
     36.17% done, estimate finish Wed Oct 31 11:24:46 2018
     45.22% done, estimate finish Wed Oct 31 11:24:46 2018
     54.25% done, estimate finish Wed Oct 31 11:24:46 2018
     63.31% done, estimate finish Wed Oct 31 11:24:46 2018
     72.34% done, estimate finish Wed Oct 31 11:24:46 2018
     81.39% done, estimate finish Wed Oct 31 11:24:46 2018
     90.42% done, estimate finish Wed Oct 31 11:24:46 2018
     99.48% done, estimate finish Wed Oct 31 11:24:46 2018
    Total translation table size: 0
    Total rockridge attributes bytes: 358
    Total directory bytes: 0
    Path table size(bytes): 10
    Max brk space used 0
    55297 extents written (108 MB)
  5. Create a driver installation script for your Compute nodes. This script installs the NVIDIA GRID host driver on each Compute node that you run it on. The following example creates a script named install_nvidia.sh:

    #/bin/bash
    
    # NVIDIA GRID package
    mkdir /tmp/mount
    mount LABEL=NVIDIA /tmp/mount
    rpm -ivh /tmp/mount/NVIDIA-vGPU-rhel-8.1-430.27.x86_64.rpm
  6. Customize the overcloud image by attaching the ISO image that you generated in Step 4, and running the driver installation script that you created in Step 5:

    $ virt-customize --attach nvidia-packages.iso -a overcloud-full-gpu.qcow2  -v --run install_nvidia.sh
    [   0.0] Examining the guest ...
    libguestfs: launch: program=virt-customize
    libguestfs: launch: version=1.36.10rhel=8,release=6.el8_5.2,libvirt
    libguestfs: launch: backend registered: unix
    libguestfs: launch: backend registered: uml
    libguestfs: launch: backend registered: libvirt
  7. Relabel the customized image with SELinux:

    $ virt-customize -a overcloud-full-gpu.qcow2 --selinux-relabel
    [   0.0] Examining the guest ...
    [   2.2] Setting a random seed
    [   2.2] SELinux relabelling
    [  27.4] Finishing off
  8. Prepare the custom image files for upload to the OpenStack Image Service:

    $ mkdir /var/image/x86_64/image
    $ guestmount -a overcloud-full-gpu.qcow2 -i --ro image
    $ cp image/boot/vmlinuz-3.10.0-862.14.4.el8.x86_64 ./overcloud-full-gpu.vmlinuz
    $ cp image/boot/initramfs-3.10.0-862.14.4.el8.x86_64.img ./overcloud-full-gpu.initrd
  9. From the undercloud, upload the custom image to the OpenStack Image Service:

    (undercloud) $ openstack overcloud image upload --update-existing --os-image-name overcloud-full-gpu.qcow2

8.2.2. Designating Compute nodes for vGPU

To designate Compute nodes for vGPU workloads, you must create a new role file to configure the vGPU role, and configure a new flavor to use to tag the GPU-enabled Compute nodes.

Procedure

  1. To create the new ComputeGPU role file, copy the file /usr/share/openstack-tripleo-heat-templates/roles/Compute.yaml to /usr/share/openstack-tripleo-heat-templates/roles/ComputeGPU.yaml and edit the following file sections:

    Table 8.1. ComputeGPU role file edits

    Section/ParameterCurrent valueNew value

    Role comment

    Role: Compute

    Role: ComputeGpu

    Role name

    name: Compute

    name: ComputeGpu

    description

    Basic Compute Node role

    GPU Compute Node role

    ImageDefault

    overcloud-full

    overcloud-full-gpu

    HostnameFormatDefault

    -compute-

    -computegpu-

    deprecated_nic_config_name

    compute.yaml

    compute-gpu.yaml

  2. Generate a new roles data file named gpu_roles_data.yaml that includes the Controller, Compute, and ComputeGpu roles.

    (undercloud) [stack@director templates]$ openstack overcloud roles generate -o /home/stack/templates/gpu_roles_data.yaml Controller Compute ComputeGpu

    The following example shows the ComputeGpu role details:

    #####################################################################
    # Role: ComputeGpu                                                  #
    #####################################################################
    - name: ComputeGpu
      description: |
        GPU Compute Node role
      CountDefault: 1
      ImageDefault: overcloud-full-gpu
      networks:
        - InternalApi
        - Tenant
        - Storage
      HostnameFormatDefault: '%stackname%-computegpu-%index%'
      RoleParametersDefault:
        TunedProfileName: "virtual-host"
      # Deprecated & backward-compatible values (FIXME: Make parameters consistent)
      # Set uses_deprecated_params to True if any deprecated params are used.
      uses_deprecated_params: True
      deprecated_param_image: 'NovaImage'
      deprecated_param_extraconfig: 'NovaComputeExtraConfig'
      deprecated_param_metadata: 'NovaComputeServerMetadata'
      deprecated_param_scheduler_hints: 'NovaComputeSchedulerHints'
      deprecated_param_ips: 'NovaComputeIPs'
      deprecated_server_resource_name: 'NovaCompute'
      deprecated_nic_config_name: 'compute-gpu.yaml'
      ServicesDefault:
        - OS::TripleO::Services::Aide
        - OS::TripleO::Services::AuditD
        - OS::TripleO::Services::CACerts
        - OS::TripleO::Services::CephClient
        - OS::TripleO::Services::CephExternal
        - OS::TripleO::Services::CertmongerUser
        - OS::TripleO::Services::Collectd
        - OS::TripleO::Services::ComputeCeilometerAgent
        - OS::TripleO::Services::ComputeNeutronCorePlugin
        - OS::TripleO::Services::ComputeNeutronL3Agent
        - OS::TripleO::Services::ComputeNeutronMetadataAgent
        - OS::TripleO::Services::ComputeNeutronOvsAgent
        - OS::TripleO::Services::Docker
        - OS::TripleO::Services::Fluentd
        - OS::TripleO::Services::Ipsec
        - OS::TripleO::Services::Iscsid
        - OS::TripleO::Services::Kernel
        - OS::TripleO::Services::LoginDefs
        - OS::TripleO::Services::MetricsQdr
        - OS::TripleO::Services::MySQLClient
        - OS::TripleO::Services::NeutronBgpVpnBagpipe
        - OS::TripleO::Services::NeutronLinuxbridgeAgent
        - OS::TripleO::Services::NeutronVppAgent
        - OS::TripleO::Services::NovaCompute
        - OS::TripleO::Services::NovaLibvirt
        - OS::TripleO::Services::NovaLibvirtGuests
        - OS::TripleO::Services::NovaMigrationTarget
        - OS::TripleO::Services::Ntp
        - OS::TripleO::Services::ContainersLogrotateCrond
        - OS::TripleO::Services::OpenDaylightOvs
        - OS::TripleO::Services::Rhsm
        - OS::TripleO::Services::RsyslogSidecar
        - OS::TripleO::Services::Securetty
        - OS::TripleO::Services::SensuClient
        - OS::TripleO::Services::SkydiveAgent
        - OS::TripleO::Services::Snmp
        - OS::TripleO::Services::Sshd
        - OS::TripleO::Services::Timezone
        - OS::TripleO::Services::TripleoFirewall
        - OS::TripleO::Services::TripleoPackages
        - OS::TripleO::Services::Tuned
        - OS::TripleO::Services::Vpp
        - OS::TripleO::Services::OVNController
        - OS::TripleO::Services::OVNMetadataAgent
        - OS::TripleO::Services::Ptp
  3. Register the node for the overcloud. For more information, see Registering nodes for the overcloud in the Director Installation and Usage guide.
  4. Inspect the node hardware. For more information, see Inspecting the hardware of nodes in the Director Installation and Usage guide.
  5. Create the compute-vgpu-nvidia flavor to use to tag nodes that you want to designate for vGPU workloads:

    (undercloud) [stack@director templates]$ openstack flavor create --id auto --ram 6144 --disk 40 --vcpus 4 compute-vgpu-nvidia
    +----------------------------+--------------------------------------+
    | Field                      | Value                                |
    +----------------------------+--------------------------------------+
    | OS-FLV-DISABLED:disabled   | False                                |
    | OS-FLV-EXT-DATA:ephemeral  | 0                                    |
    | disk                       | 40                                   |
    | id                         | 9cb47954-be00-47c6-a57f-44db35be3e69 |
    | name                       | compute-vgpu-nvidia                  |
    | os-flavor-access:is_public | True                                 |
    | properties                 |                                      |
    | ram                        | 6144                                 |
    | rxtx_factor                | 1.0                                  |
    | swap                       |                                      |
    | vcpus                      | 4                                    |
    +----------------------------+--------------------------------------+
  6. Tag each node that you want to designate for GPU workloads with the compute-vgpu-nvidia profile.

    (undercloud) [stack@director templates]$ openstack baremetal node set --property capabilities='profile:compute-vgpu-nvidia,boot_option:local' <node>

    Replace <node> with the ID of the baremetal node.

8.2.3. Configuring the Compute node for vGPU and deploying the overcloud

You need to retrieve and assign the vGPU type that corresponds to the physical GPU device in your environment, and prepare the environment files to configure the Compute node for vGPU.

Procedure

  1. Install Red Hat Enterprise Linux and the NVIDIA GRID driver on a temporary Compute node and launch the node. For more information about installing the NVIDIA GRID driver, see Section 8.2.1, “Building a custom GPU overcloud image”.
  2. On the Compute node, locate the vGPU type of the physical GPU device that you want to enable. For libvirt, virtual GPUs are mediated devices, or mdev type devices. To discover the supported mdev devices, enter the following command:

    [root@overcloud-computegpu-0 ~]# ls /sys/class/mdev_bus/0000\:06\:00.0/mdev_supported_types/
    nvidia-11  nvidia-12  nvidia-13  nvidia-14  nvidia-15  nvidia-16  nvidia-17  nvidia-18  nvidia-19  nvidia-20  nvidia-21  nvidia-210  nvidia-22
    
    [root@overcloud-computegpu-0 ~]# cat /sys/class/mdev_bus/0000\:06\:00.0/mdev_supported_types/nvidia-18/description
    num_heads=4, frl_config=60, framebuffer=2048M, max_resolution=4096x2160, max_instance=4
  3. Add the compute-gpu.yaml file to the network-environment.yaml file:

    resource_registry:
      OS::TripleO::Compute::Net::SoftwareConfig: /home/stack/templates/nic-configs/compute.yaml
      OS::TripleO::ComputeGpu::Net::SoftwareConfig: /home/stack/templates/nic-configs/compute-gpu.yaml
      OS::TripleO::Controller::Net::SoftwareConfig: /home/stack/templates/nic-configs/controller.yaml
      #OS::TripleO::AllNodes::Validation: OS::Heat::None
  4. Add the following parameters to the node-info.yaml file to specify the number of GPU Compute nodes, and the flavor to use for the GPU-designated Compute nodes:

    parameter_defaults:
      OvercloudControllerFlavor: control
      OvercloudComputeFlavor: compute
      OvercloudComputeGpuFlavor: compute-vgpu-nvidia
      ControllerCount: 1
      ComputeCount: 0
      ComputeGpuCount: 1
  5. Create a gpu.yaml file to specify the vGPU type of your GPU device:

    parameter_defaults:
      ComputeGpuExtraConfig:
        nova::compute::vgpu::enabled_vgpu_types:
          - nvidia-18
    Note

    Each physical GPU supports only one virtual GPU type. If you specify multiple vGPU types in this property, only the first type is used.

  6. Deploy the overcloud, adding your new role and environment files to the stack along with your other environment files:

    (undercloud) $ openstack overcloud deploy --templates \
      -r /home/stack/templates/nvidia/gpu_roles_data.yaml
      -e /home/stack/templates/node-info.yaml
      -e /home/stack/templates/network-environment.yaml
      -e [your environment files]
      -e /home/stack/templates/gpu.yaml

8.3. Creating the vGPU image and flavor

To enable your cloud users to create instances that use a virtual GPU (vGPU), you can define a custom vGPU-enabled image, and you can create a vGPU flavor.

8.3.1. Creating a custom GPU instance image

After you deploy the overcloud with GPU-enabled Compute nodes, you can create a custom vGPU-enabled instance image with the NVIDIA GRID guest driver and license file.

Procedure

  1. Create an instance with the hardware and software profile that your vGPU instances require:

    (overcloud) [stack@director ~]$ openstack server create --flavor <flavor> --image <image> temp_vgpu_instance
    • Replace <flavor> with the name or ID of the flavor that has the hardware profile that your vGPU instances require. For information on default flavors, see Manage flavors.
    • Replace <image> with the name or ID of the image that has the software profile that your vGPU instances require. For information on downloading RHEL cloud images, see Image service.
  2. Log in to the instance as a cloud-user. For more information, see Log in to an Instance.
  3. Create the gridd.conf NVIDIA GRID license file on the instance, following the NVIDIA guidance: Licensing an NVIDIA vGPU on Linux by Using a Configuration File.
  4. Install the GPU driver on the instance. For more information about installing an NVIDIA driver, see Installing the NVIDIA vGPU Software Graphics Driver on Linux.

    Note

    Use the hw_video_model image property to define the GPU driver type. You can choose none if you want to disable the emulated GPUs for your vGPU instances. For more information about supported drivers, see Appendix A, Image configuration parameters.

  5. Create an image snapshot of the instance:

    (overcloud) [stack@director ~]$ openstack server image create --name vgpu_image temp_vgpu_instance
  6. Optional: Delete the instance.

8.3.2. Creating a vGPU flavor for instances

After you deploy the overcloud with GPU-enabled Compute nodes, you can create a custom flavor that your cloud users can use to launch instances for GPU workloads.

Procedure

  1. Create an NVIDIA GPU flavor. For example:

    (overcloud) [stack@virtlab-director2 ~]$ openstack flavor create --vcpus 6 --ram 8192 --disk 100 m1.small-gpu
    +----------------------------+--------------------------------------+
    | Field                      | Value                                |
    +----------------------------+--------------------------------------+
    | OS-FLV-DISABLED:disabled   | False                                |
    | OS-FLV-EXT-DATA:ephemeral  | 0                                    |
    | disk                       | 100                                  |
    | id                         | a27b14dd-c42d-4084-9b6a-225555876f68 |
    | name                       | m1.small-gpu                         |
    | os-flavor-access:is_public | True                                 |
    | properties                 |                                      |
    | ram                        | 8192                                 |
    | rxtx_factor                | 1.0                                  |
    | swap                       |                                      |
    | vcpus                      | 6                                    |
    +----------------------------+--------------------------------------+
  2. Assign a vGPU resource to the flavor that you created. You can assign only one vGPU for each instance.

    (overcloud) [stack@virtlab-director2 ~]$ openstack flavor set m1.small-gpu --property "resources:VGPU=1"
    
    (overcloud) [stack@virtlab-director2 ~]$ openstack flavor show m1.small-gpu
    +----------------------------+--------------------------------------+
    | Field                      | Value                                |
    +----------------------------+--------------------------------------+
    | OS-FLV-DISABLED:disabled   | False                                |
    | OS-FLV-EXT-DATA:ephemeral  | 0                                    |
    | access_project_ids         | None                                 |
    | disk                       | 100                                  |
    | id                         | a27b14dd-c42d-4084-9b6a-225555876f68 |
    | name                       | m1.small-gpu                         |
    | os-flavor-access:is_public | True                                 |
    | properties                 | resources:VGPU='1'                   |
    | ram                        | 8192                                 |
    | rxtx_factor                | 1.0                                  |
    | swap                       |                                      |
    | vcpus                      | 6                                    |
    +----------------------------+--------------------------------------+

8.3.3. Launching a vGPU instance

You can create a GPU-enabled instance for GPU workloads.

Procedure

  1. Create an instance using a GPU flavor and image. For example:

    (overcloud) [stack@virtlab-director2 ~]$ openstack server create --flavor m1.small-gpu --image vgpu_image --security-group web --nic net-id=internal0 --key-name lambda vgpu-instance
  2. Log in to the instance as a cloud-user. For more information, see Log in to an Instance.
  3. To verify that the GPU is accessible from the instance, run the following command from the instance:

    $ lspci -nn | grep <gpu_name>

Appendix A. Image configuration parameters

The following keys can be used with the property option for both the glance image-update and glance image-create commands.

$ glance image-update IMG-UUID --property architecture=x86_64
Note

Behavior set using image properties overrides behavior set using flavors. For more information, see Section 4.3, “Managing flavors”.

Table A.1. Property Keys

Specific toKeyDescriptionSupported values

All

architecture

The CPU architecture that must be supported by the hypervisor. For example, x86_64, arm, or ppc64. Run uname -m to get the architecture of a machine. We strongly recommend using the architecture data vocabulary defined by the libosinfo project for this purpose.

  • alpha-DEC 64-bit RISC
  • armv7l-ARM Cortex-A7 MPCore
  • cris-Ethernet, Token Ring, AXis-Code Reduced Instruction Set
  • i686-Intel sixth-generation x86 (P6 micro architecture)
  • ia64-Itanium
  • lm32-Lattice Micro32
  • m68k-Motorola 68000
  • microblaze-Xilinx 32-bit FPGA (Big Endian)
  • microblazeel-Xilinx 32-bit FPGA (Little Endian)
  • mips-MIPS 32-bit RISC (Big Endian)
  • mipsel-MIPS 32-bit RISC (Little Endian)
  • mips64-MIPS 64-bit RISC (Big Endian)
  • mips64el-MIPS 64-bit RISC (Little Endian)
  • openrisc-OpenCores RISC
  • parisc-HP Precision Architecture RISC
  • parisc64-HP Precision Architecture 64-bit RISC
  • ppc-PowerPC 32-bit
  • ppc64-PowerPC 64-bit
  • ppcemb-PowerPC (Embedded 32-bit)
  • s390-IBM Enterprise Systems Architecture/390
  • s390x-S/390 64-bit
  • sh4-SuperH SH-4 (Little Endian)
  • sh4eb-SuperH SH-4 (Big Endian)
  • sparc-Scalable Processor Architecture, 32-bit
  • sparc64-Scalable Processor Architecture, 64-bit
  • unicore32-Microprocessor Research and Development Center RISC Unicore32
  • x86_64-64-bit extension of IA-32
  • xtensa-Tensilica Xtensa configurable microprocessor core
  • xtensaeb-Tensilica Xtensa configurable microprocessor core (Big Endian)

All

hypervisor_type

The hypervisor type.

kvm, vmware

All

instance_uuid

For snapshot images, this is the UUID of the server used to create this image.

Valid server UUID

All

kernel_id

The ID of an image stored in the Image Service that should be used as the kernel when booting an AMI-style image.

Valid image ID

All

os_distro

The common name of the operating system distribution in lowercase (uses the same data vocabulary as the libosinfo project). Specify only a recognized value for this field. Deprecated values are listed to assist you in searching for the recognized value.

  • arch-Arch Linux. Do not use archlinux or org.archlinux
  • centos-Community Enterprise Operating System. Do not use org.centos or CentOS
  • debian-Debian. Do not use Debian or org.debian
  • fedora-Fedora. Do not use Fedora, org.fedora, or org.fedoraproject
  • freebsd-FreeBSD. Do not use org.freebsd, freeBSD, or FreeBSD
  • gentoo-Gentoo Linux. Do not use Gentoo or org.gentoo
  • mandrake-Mandrakelinux (MandrakeSoft) distribution. Do not use mandrakelinux or MandrakeLinux
  • mandriva-Mandriva Linux. Do not use mandrivalinux
  • mes-Mandriva Enterprise Server. Do not use mandrivaent or mandrivaES
  • msdos-Microsoft Disc Operating System. Do not use ms-dos
  • netbsd-NetBSD. Do not use NetBSD or org.netbsd
  • netware-Novell NetWare. Do not use novell or NetWare
  • openbsd-OpenBSD. Do not use OpenBSD or org.openbsd
  • opensolaris-OpenSolaris. Do not use OpenSolaris or org.opensolaris
  • opensuse-openSUSE. Do not use suse, SuSE, or org.opensuse
  • rhel-Red Hat Enterprise Linux. Do not use redhat, RedHat, or com.redhat
  • sled-SUSE Linux Enterprise Desktop. Do not use com.suse
  • ubuntu-Ubuntu. Do not use Ubuntu, com.ubuntu, org.ubuntu, or canonical
  • windows-Microsoft Windows. Do not use com.microsoft.server

All

os_version

The operating system version as specified by the distributor.

Version number (for example, "11.10")

All

ramdisk_id

The ID of image stored in the Image Service that should be used as the ramdisk when booting an AMI-style image.

Valid image ID

All

vm_mode

The virtual machine mode. This represents the host/guest ABI (application binary interface) used for the virtual machine.

hvm-Fully virtualized. This is the mode used by QEMU and KVM.

libvirt API driver

hw_disk_bus

Specifies the type of disk controller to attach disk devices to.

scsi, virtio, ide, or usb. Note that if using iscsi, the hw_scsi_model needs to be set to virtio-scsi.

libvirt API driver

hw_numa_nodes

Number of NUMA nodes to expose to the instance (does not override flavor definition).

Integer. For a detailed example of NUMA-topology definition, see the hw:NUMA_def key in Add Metadata.

libvirt API driver

hw_numa_cpus.0

Mapping of vCPUs N-M to NUMA node 0 (does not override flavor definition).

Comma-separated list of integers.

libvirt API driver

hw_numa_cpus.1

Mapping of vCPUs N-M to NUMA node 1 (does not override flavor definition).

Comma-separated list of integers.

libvirt API driver

hw_numa_mem.0

Mapping N MB of RAM to NUMA node 0 (does not override flavor definition).

Integer

libvirt API driver

hw_numa_mem.1

Mapping N MB of RAM to NUMA node 1 (does not override flavor definition).

Integer

libvirt API driver

hw_qemu_guest_agent

Guest agent support. If set to yes, and if qemu-ga is also installed, file systems can be quiesced (frozen) and snapshots created automatically.

yes / no

libvirt API driver

hw_rng_model

Adds a random-number generator device to the image’s instances. The cloud administrator can enable and control device behavior by configuring the instance’s flavor. By default:

  • The generator device is disabled.
  • /dev/random is used as the default entropy source. To specify a physical HW RNG device, set rng_dev_path to "/dev/hwrng" in your Compute environment file.

virtio, or other supported device.

libvirt API driver

hw_scsi_model

Enables the use of VirtIO SCSI (virtio-scsi) to provide block device access for compute instances; by default, instances use VirtIO Block (virtio-blk). VirtIO SCSI is a para-virtualized SCSI controller device that provides improved scalability and performance, and supports advanced SCSI hardware.

virtio-scsi

libvirt API driver

hw_video_model

The video image driver used.

vga, cirrus, vmvga, xen, or qxl

libvirt API driver

hw_video_ram

Maximum RAM for the video image. Used only if a hw_video:ram_max_mb value has been set in the flavor’s extra_specs and that value is higher than the value set in hw_video_ram.

Integer in MB (for example, 64)

libvirt API driver

hw_watchdog_action

Enables a virtual hardware watchdog device that carries out the specified action if the server hangs. The watchdog uses the i6300esb device (emulating a PCI Intel 6300ESB). If hw_watchdog_action is not specified, the watchdog is disabled.

  • disabled-The device is not attached. Allows the user to disable the watchdog for the image, even if it has been enabled using the image’s flavor. The default value for this parameter is disabled.
  • reset-Forcefully reset the guest.
  • poweroff-Forcefully power off the guest.
  • pause-Pause the guest.
  • none-Only enable the watchdog; do nothing if the server hangs.

libvirt API driver

os_command_line

The kernel command line to be used by the libvirt driver, instead of the default. For Linux Containers (LXC), the value is used as arguments for initialization. This key is valid only for Amazon kernel, ramdisk, or machine images (aki, ari, or ami).

 

libvirt API driver and VMware API driver

hw_vif_model

Specifies the model of virtual network interface device to use.

The valid options depend on the configured hypervisor.

  • KVM and QEMU: e1000, ne2k_pci, pcnet, rtl8139, and virtio.
  • VMware: e1000, e1000e, VirtualE1000, VirtualE1000e, VirtualPCNet32, VirtualSriovEthernetCard, and VirtualVmxnet.
  • Xen: e1000, netfront, ne2k_pci, pcnet, and rtl8139.

VMware API driver

vmware_adaptertype

The virtual SCSI or IDE controller used by the hypervisor.

lsiLogic, busLogic, or ide

VMware API driver

vmware_ostype

A VMware GuestID which describes the operating system installed in the image. This value is passed to the hypervisor when creating a virtual machine. If not specified, the key defaults to otherGuest.

See thinkvirt.com.

VMware API driver

vmware_image_version

Currently unused.

1

XenAPI driver

auto_disk_config

If true, the root partition on the disk is automatically resized before the instance boots. This value is only taken into account by the Compute service when using a Xen-based hypervisor with the XenAPI driver. The Compute service will only attempt to resize if there is a single partition on the image, and only if the partition is in ext3 or ext4 format.

true / false

libvirt API driver and XenAPI driver

os_type

The operating system installed on the image. The XenAPI driver contains logic that takes different actions depending on the value of the os_type parameter of the image. For example, for os_type=windows images, it creates a FAT32-based swap partition instead of a Linux swap partition, and it limits the injected host name to less than 16 characters.

linux or windows

Appendix B. Enabling the launch instance wizard

There are two methods that you can use to launch instances from the dashboard:

  • The Launch Instance form
  • The Launch Instance wizard

The Launch Instance form is enabled by default, but you can enable the Launch Instance wizard at any time. You can also enable both the Launch Instance form and the Launch Instance wizard at the same time. The Launch Instance wizard simplifies the steps required to create instances.

  1. Edit /etc/openstack-dashboard/local_settings file, and add the following values:

    LAUNCH_INSTANCE_LEGACY_ENABLED = False
    LAUNCH_INSTANCE_NG_ENABLED = True
  2. Restart the httpd service:

    # systemctl restart httpd

The preferences for the Launch Instance form and Launch Instance wizard are updated.

If you enabled only one of these options, the Launch Instance button in the dashboard opens that option by default. If you enabled both options, two Launch Instance buttons are displayed in the dashboard, with the button on the left opening the Launch Instance wizard and the button on the right opening the Launch Instance form.

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