Chapter 2. Block Storage and Volumes

The Block Storage service (openstack-cinder) manages the administration, security, scheduling, and overall management of all volumes. Volumes are used as the primary form of persistent storage for Compute instances.

For more information about volume backups, refer to the Block Storage Backup Guide.

2.1. Back Ends

Red Hat OpenStack Platform is deployed using the OpenStack Platform director. Doing so helps ensure the proper configuration of each service, including the Block Storage service (and, by extension, its back end). The director also has several integrated back end configurations.

Red Hat OpenStack Platform supports Red Hat Ceph and NFS as Block Storage back ends. By default, the Block Storage service uses an LVM back end as a repository for volumes. While this back end is suitable for test environments, LVM is not supported in production environments.

For instructions on how to deploy Ceph with OpenStack, see Deploying an Overcloud with Containerized Red Hat Ceph.

For instructions on how to set up NFS storage in the overcloud, see Configuring NFS Storage (from the Advanced Overcloud Customization Guide).

2.1.1. Third-Party Storage Providers

You can also configure the Block Storage service to use supported third-party storage appliances. The director includes the necessary components for easily deploying different backend solutions.

For a complete list of supported back end appliances and drivers, see Component, Plug-In, and Driver Support in RHEL OpenStack Platform. Some back ends have individual guides, which are available on the Red Hat OpenStack Storage documentation site.

2.2. Block Storage Service Administration

The following procedures explain how to configure the Block Storage service to suit your needs. All of these procedures require administrator privileges.

Important

You must install host bus adapters (HBAs) on all Controller nodes and Compute nodes in any deployment that uses the Block Storage service (cinder) and a Fibre Channel (FC) back end.

2.2.1. Active-active deployment for high availability

Important
Active-active mode is supported only in distributed compute node (DCN) architecture at edge sites.

In active-passive mode, if the Block Storage service fails in a hyperconverged deployment, node fencing is undesirable. This is because node fencing can trigger storage to be rebalanced unnecessarily. Edge sites do not deploy Pacemaker, although Pacemaker is still present at the control site. Instead, edge sites deploy the Block Storage service in an active-active configuration to support highly available hyperconverged deployments.

Active-active deployments improve scaling, performance, and reduce response time by balancing workloads across all available nodes. Deploying the Block Storage service in an active-active configuration creates a highly available environment that maintains the management layer during partial network outages and single- or multi-node hardware failures. Active-active deployments allow a cluster to continue providing Block Storage services during a node outage.

Active-active deployments do not, however, enable workflows to resume automatically. If a service stops, individual operations running on the failed node will also fail during the outage. In this situation, confirm that the service is down and initiate a cleanup of resources that had in-flight operations.

2.2.1.1. Enabling active-active configuration for high availability

The cinder-volume-active-active.yaml file enables you to deploy the Block Storage service in an active-active configuration. This file ensures director uses the non-Pacemaker cinder-volume heat template and adds the etcd service to the deployment as a distributed lock manager (DLM).

The cinder-volume-active-active.yaml file also defines the active-active cluster name by assigning a value to the CinderVolumeCluster parameter. CinderVolumeCluster is a global Block Storage parameter. Therefore, you cannot include clustered (active-active) and non-clustered back ends in the same deployment.

Important

Currently, active-active configuration for Block Storage works only with Ceph RADOS Block Device (RBD) back ends. If you plan to use multiple back ends, all back ends must support the active-active configuration. If a back end that does not support the active-active configuration is included in the deployment, that back end will not be available for storage. In an active-active deployment, you risk data loss if you save data on a back end that does not support the active-active configuration.

Procedure

To enable active-active Block Storage service volumes, include the following environment file in your overcloud deployment:

-e /usr/share/openstack-tripleo-heat-templates/environments/cinder-volume-active-active.yaml

2.2.1.2. Maintenance commands for active-active configurations

After deploying an active-active configuration, there are several commands you can use to interact with the environment when using API version 3.17 and later.

User goal

Command

See the service listing, including details such as cluster name, host, zone, status, state, disabled reason, and back end state.

NOTE: When deployed by director for the Ceph back end, the default cluster name is tripleo@tripleo_ceph.

cinder service-list

See detailed and summary information about clusters as a whole as opposed to individual services.

cinder cluster-list

NOTE: This command requires a cinder API microversion of 3.7 or later.

See detailed information about a specific cluster.

cinder cluster-show <cluster_name>

NOTE: This command requires a cinder API microversion of 3.7 or later.

Enable a disabled service.

cinder cluster-enable <cluster_name>

NOTE: This command requires a cinder API microversion of 3.7 or later.

Disable a clustered service.

cinder cluster-disable <cluster_name>

NOTE: This command requires a cinder API microversion of 3.7 or later.

2.2.1.3. Volume manage and unmanage

The unmanage and manage mechanisms facilitate moving volumes from one service using version X to another service using version X+1. Both services remain running during this process.

In API version 3.17 or later, you can see lists of volumes and snapshots that are available for management in Block Storage clusters. To see these lists, use the --cluster argument with cinder manageable-list or cinder snapshot-manageable-list.

In API version 3.16 and later, the cinder manage command also accepts the optional --cluster argument so that you can add previously unmanaged volumes to a Block Storage cluster.

2.2.1.4. Volume migration on a clustered service

With API version 3.16 and later, the cinder migrate and cinder-manage commands accept the --cluster argument to define the destination for active-active deployments.

When you migrate a volume on a Block Storage clustered service, pass the optional --cluster argument and omit the host positional argument, because the arguments are mutually exclusive.

2.2.1.5. Initiating server maintenance

All Block Storage volume services perform their own maintenance when they start. In an environment with multiple volume services grouped in a cluster, you can clean up services that are not currently running.

The command work-cleanup triggers server cleanups. The command returns:

  • A list of the services that the command can clean.
  • A list of the services that the command cannot clean because they are not currently running in the cluster.
Note

The work-cleanup command works only on servers running API version 3.24 or later.

Procedure

  1. Run the following command to verify whether all of the services for a cluster are running:

    $ cinder cluster-list --detailed

    Alternatively, run the cluster show command.

  2. If any services are not running, run the following command to identify those specific services:

    $ cinder service-list
  3. Run the following command to trigger the server cleanup:

    $ cinder work-cleanup [--cluster <cluster-name>] [--host <hostname>] [--binary <binary>] [--is-up <True|true|False|false>] [--disabled <True|true|False|false>] [--resource-id <resource-id>] [--resource-type <Volume|Snapshot>]
    Note

    Filters, such as --cluster, --host, and --binary, define what the command cleans. You can filter on cluster name, host name, type of service, and resource type, including a specific resource. If you do not apply filtering, the command attempts to clean everything that can be cleaned.

    The following example filters by cluster name:

    $ cinder work-cleanup --cluster tripleo@tripleo_ceph

2.2.2. Group Volume Settings with Volume Types

With Red Hat OpenStack Platform you can create volume types so that you can apply associated settings to the volume type. You can apply settings during volume creation, see Create a Volume. You can also apply settings after you create a volume, see Changing the Type of a Volume (Volume Re-typing). The following list shows some of the associated setting that you can apply to a volume type:

Settings are associated with volume types using key-value pairs called Extra Specs. When you specify a volume type during volume creation, the Block Storage scheduler applies these key-value pairs as settings. You can associate multiple key-value pairs to the same volume type.

Volume types provide the capability to provide different users with storage tiers. By associating specific performance, resilience, and other settings as key-value pairs to a volume type, you can map tier-specific settings to different volume types. You can then apply tier settings when creating a volume by specifying the corresponding volume type.

2.2.2.1. List the Capabilities of a Host Driver

Note

Available and supported Extra Specs vary per back end driver. Consult the driver documentation for a list of valid Extra Specs.

Alternatively, you can query the Block Storage host directly to determine which well-defined standard Extra Specs are supported by its driver. Start by logging in (through the command line) to the node hosting the Block Storage service. Then:

# cinder service-list

This command will return a list containing the host of each Block Storage service (cinder-backup, cinder-scheduler, and cinder-volume). For example:

+------------------+---------------------------+------+---------
|      Binary      |            Host           | Zone |  Status ...
+------------------+---------------------------+------+---------
|  cinder-backup   |   localhost.localdomain   | nova | enabled ...
| cinder-scheduler |   localhost.localdomain   | nova | enabled ...
|  cinder-volume   | *localhost.localdomain@lvm* | nova | enabled ...
+------------------+---------------------------+------+---------

To display the driver capabilities (and, in turn, determine the supported Extra Specs) of a Block Storage service, run:

# cinder get-capabilities _VOLSVCHOST_

Where VOLSVCHOST is the complete name of the cinder-volume's host. For example:

# cinder get-capabilities localhost.localdomain@lvm
    +---------------------+-----------------------------------------+
    |     Volume stats    |                        Value            |
    +---------------------+-----------------------------------------+
    |     description     |                         None            |
    |     display_name    |                         None            |
    |    driver_version   |                        3.0.0            |
    |      namespace      | OS::Storage::Capabilities::localhost.loc...
    |      pool_name      |                         None            |
    |   storage_protocol  |                        iSCSI            |
    |     vendor_name     |                     Open Source         |
    |      visibility     |                         None            |
    | volume_backend_name |                         lvm             |
    +---------------------+-----------------------------------------+
    +--------------------+------------------------------------------+
    | Backend properties |                        Value             |
    +--------------------+------------------------------------------+
    |    compression     |      {u'type': u'boolean', u'description'...
    |        qos         |              {u'type': u'boolean', u'des ...
    |    replication     |      {u'type': u'boolean', u'description'...
    | thin_provisioning  | {u'type': u'boolean', u'description': u'S...
    +--------------------+------------------------------------------+

The Backend properties column shows a list of Extra Spec Keys that you can set, while the Value column provides information on valid corresponding values.

2.2.2.2. Create and Configure a Volume Type

  1. As an admin user in the dashboard, select Admin > Volumes > Volume Types.
  2. Click Create Volume Type.
  3. Enter the volume type name in the Name field.
  4. Click Create Volume Type. The new type appears in the Volume Types table.
  5. Select the volume type’s View Extra Specs action.
  6. Click Create and specify the Key and Value. The key-value pair must be valid; otherwise, specifying the volume type during volume creation will result in an error.
  7. Click Create. The associated setting (key-value pair) now appears in the Extra Specs table.

By default, all volume types are accessible to all OpenStack tenants. If you need to create volume types with restricted access, you will need to do so through the CLI. For instructions, see Section 2.2.2.5, “Create and Configure Private Volume Types”.

Note

You can also associate a QoS Spec to the volume type. For more information, see Section 2.2.5.4, “Associate a QOS Spec with a Volume Type”.

2.2.2.3. Edit a Volume Type

  1. As an admin user in the dashboard, select Admin > Volumes > Volume Types.
  2. In the Volume Types table, select the volume type’s View Extra Specs action.
  3. On the Extra Specs table of this page, you can:

    • Add a new setting to the volume type. To do this, click Create and specify the key/value pair of the new setting you want to associate to the volume type.
    • Edit an existing setting associated with the volume type by selecting the setting’s Edit action.
    • Delete existing settings associated with the volume type by selecting the extra specs' check box and clicking Delete Extra Specs in this and the next dialog screen.

2.2.2.4. Delete a Volume Type

To delete a volume type, select its corresponding check boxes from the Volume Types table and click Delete Volume Types.

2.2.2.5. Create and Configure Private Volume Types

By default, all volume types are available to all tenants. You can create a restricted volume type by marking it private. To do so, set the type’s is-public flag to false.

Private volume types are useful for restricting access to volumes with certain attributes. Typically, these are settings that should only be usable by specific tenants; examples include new back ends or ultra-high performance configurations that are being tested.

To create a private volume type, run:

$ cinder type-create --is-public false  <TYPE-NAME>

By default, private volume types are only accessible to their creators. However, admin users can find and view private volume types using the following command:

$ cinder type-list --all

This command lists both public and private volume types, and it also includes the name and ID of each one. You need the volume type’s ID to provide access to it.

Access to a private volume type is granted at the tenant level. To grant a tenant access to a private volume type, run:

$ cinder  type-access-add --volume-type <TYPE-ID> --project-id <TENANT-ID>

To view which tenants have access to a private volume type, run:

$ cinder  type-access-list --volume-type <TYPE-ID>

To remove a tenant from the access list of a private volume type, run:

$ cinder  type-access-remove --volume-type <TYPE-ID> --project-id <TENANT-ID>
Note

By default, only users with administrative privileges can create, view, or configure access for private volume types.

2.2.3. Create and Configure an Internal Tenant for the Block Storage Service

Some Block Storage features (for example, the Image-Volume cache) require the configuration of an internal tenant. The Block Storage service uses this tenant/project to manage block storage items that do not necessarily need to be exposed to normal users. Examples of such items are images cached for frequent volume cloning or temporary copies of volumes being migrated.

To configure an internal project, first create a generic project and user, both named cinder-internal. To do so, log in to the Controller node and run:

# openstack project create --enable --description "Block Storage Internal Tenant" cinder-internal
    +-------------+----------------------------------+
    |   Property  |              Value               |
    +-------------+----------------------------------+
    | description |  Block Storage Internal Tenant   |
    |   enabled   |               True               |
    |      id     | *cb91e1fe446a45628bb2b139d7dccaef* |
    |     name    |         cinder-internal          |
    +-------------+----------------------------------+
# openstack user create --project cinder-internal cinder-internal
    +----------+----------------------------------+
    | Property |              Value               |
    +----------+----------------------------------+
    |  email   |               None               |
    | enabled  |               True               |
    |    id    | *84e9672c64f041d6bfa7a930f558d946* |
    |   name   |         cinder-internal          |
    |project_id| *cb91e1fe446a45628bb2b139d7dccaef* |
    | username |         cinder-internal          |
    +----------+----------------------------------+

The procedure for adding Extra Config options creates an internal tenant. Refer to Section 2.2.4, “Configure and Enable the Image-Volume Cache”.

2.2.4. Configure and Enable the Image-Volume Cache

The Block Storage service features an optional Image-Volume cache which can be used when creating volumes from images. This cache is designed to improve the speed of volume creation from frequently-used images. For information on how to create volumes from images, see Section 2.3.1, “Create a volume”.

When enabled, the Image-Volume cache stores a copy of an image the first time a volume is created from it. This stored image is cached locally to the Block Storage back end to help improve performance the next time the image is used to create a volume. The Image-Volume cache’s limit can be set to a size (in GB), number of images, or both.

The Image-Volume cache is supported by several back ends. If you are using a third-party back end, refer to its documentation for information on Image-Volume cache support.

Note

The Image-Volume cache requires that an internal tenant be configured for the Block Storage service. For instructions, see Section 2.2.3, “Create and Configure an Internal Tenant for the Block Storage Service”.

To enable and configure the Image-Volume cache on a back end (BACKEND), add the values to an ExtraConfig section of an environment file on the undercloud. For example:

parameter_defaults:
  ExtraConfig:
    cinder::config::cinder_config:
      DEFAULT/cinder_internal_tenant_project_id:
        value: TENANTID
      DEFAULT/cinder_internal_tenant_user_id:
        value: USERID
      BACKEND/image_volume_cache_enabled: 1
        value: True
      BACKEND/image_volume_cache_max_size_gb:
        value: MAXSIZE 2
      BACKEND/image_volume_cache_max_count:
        value: MAXNUMBER 3
1
Replace BACKEND with the name of the target back end (specifically, its volume_backend_name value).
2
By default, the Image-Volume cache size is only limited by the back end. Change MAXSIZE to a number in GB.
3
You can also set a maximum number of images using MAXNUMBER.

The Block Storage service database uses a time stamp to track when each cached image was last used to create an image. If either or both MAXSIZE and MAXNUMBER are set, the Block Storage service will delete cached images as needed to make way for new ones. Cached images with the oldest time stamp are deleted first whenever the Image-Volume cache limits are met.

After you create the environment file in /home/stack/templates/, log in as the stack user and deploy the configuration by running:

$ openstack overcloud deploy --templates \
-e /home/stack/templates/<ENV_FILE>.yaml

Where ENV_FILE.yaml is the name of the file with the ExtraConfig settings added earlier.

Important

If you passed any extra environment files when you created the overcloud, pass them again here using the -e option to avoid making undesired changes to the overcloud.

For additional information on the openstack overcloud deploy command, see Deployment command in the Director Installation and Usage Guide.

2.2.5. Use Quality-of-Service Specifications

You can map multiple performance settings to a single Quality-of-Service specification (QOS Specs). Doing so allows you to provide performance tiers for different user types.

Performance settings are mapped as key-value pairs to QOS Specs, similar to the way volume settings are associated to a volume type. However, QOS Specs are different from volume types in the following respects:

  • QOS Specs are used to apply performance settings, which include limiting read/write operations to disks. Available and supported performance settings vary per storage driver.

    To determine which QOS Specs are supported by your back end, consult the documentation of your back end device’s volume driver.

  • Volume types are directly applied to volumes, whereas QOS Specs are not. Rather, QOS Specs are associated to volume types. During volume creation, specifying a volume type also applies the performance settings mapped to the volume type’s associated QOS Specs.

2.2.5.1. Basic volume Quality of Service

You can define performance limits for volumes on a per-volume basis using basic volume QOS values. The Block Storage service supports the following options:

  • read_iops_sec
  • write_iops_sec
  • total_iops_sec
  • read_bytes_sec
  • write_bytes_sec
  • total_bytes_sec
  • read_iops_sec_max
  • write_iops_sec_max
  • total_iops_sec_max
  • read_bytes_sec_max
  • write_bytes_sec_max
  • total_bytes_sec_max
  • size_iops_sec

2.2.5.2. Create and Configure a QOS Spec

As an administrator, you can create and configure a QOS Spec through the QOS Specs table. You can associate more than one key/value pair to the same QOS Spec.

  1. As an admin user in the dashboard, select Admin > Volumes > Volume Types.
  2. On the QOS Specs table, click Create QOS Spec.
  3. Enter a name for the QOS Spec.
  4. In the Consumer field, specify where the QOS policy should be enforced:

    Table 2.1. Consumer Types

    TypeDescription

    back-end

    QOS policy will be applied to the Block Storage back end.

    front-end

    QOS policy will be applied to Compute.

    both

    QOS policy will be applied to both Block Storage and Compute.

  5. Click Create. The new QOS Spec should now appear in the QOS Specs table.
  6. In the QOS Specs table, select the new spec’s Manage Specs action.
  7. Click Create, and specify the Key and Value. The key-value pair must be valid; otherwise, specifying a volume type associated with this QOS Spec during volume creation will fail.

    For example, to set read limit IOPS to 500, use the following Key/Value pair:

    read_iops_sec=500
  8. Click Create. The associated setting (key-value pair) now appears in the Key-Value Pairs table.

2.2.5.3. Set Capacity-Derived QoS Limits

You can use volume types to implement capacity-derived Quality-of-Service (QoS) limits on volumes. This will allow you to set a deterministic IOPS throughput based on the size of provisioned volumes. Doing this simplifies how storage resources are provided to users — namely, providing a user with pre-determined (and, ultimately, highly predictable) throughput rates based on the volume size they provision.

In particular, the Block Storage service allows you to set how much IOPS to allocate to a volume based on the actual provisioned size. This throughput is set on an IOPS per GB basis through the following QoS keys:

read_iops_sec_per_gb
write_iops_sec_per_gb
total_iops_sec_per_gb

These keys allow you to set read, write, or total IOPS to scale with the size of provisioned volumes. For example, if the volume type uses read_iops_sec_per_gb=500, then a provisioned 3GB volume would automatically have a read IOPS of 1500.

Capacity-derived QoS limits are set per volume type, and configured like any normal QoS spec. In addition, these limits are supported by the underlying Block Storage service directly, and is not dependent on any particular driver.

For more information about volume types, see Section 2.2.2, “Group Volume Settings with Volume Types” and Section 2.2.2.2, “Create and Configure a Volume Type”. For instructions on how to set QoS specs, Section 2.2.5, “Use Quality-of-Service Specifications”.

Warning

When you apply a volume type (or perform a volume re-type) with capacity-derived QoS limits to an attached volume, the limits will not be applied. The limits will only be applied once you detach the volume from its instance.

See Section 2.3.16, “Volume retyping” for information about volume re-typing.

2.2.5.4. Associate a QOS Spec with a Volume Type

As an administrator, you can associate a QOS Spec to an existing volume type using the Volume Types table.

  1. As an administrator in the dashboard, select Admin > Volumes > Volume Types.
  2. In the Volume Types table, select the type’s Manage QOS Spec Association action.
  3. Select a QOS Spec from the QOS Spec to be associated list.
  4. Click Associate. The selected QOS Spec now appears in the Associated QOS Spec column of the edited volume type.

2.2.5.5. Disassociate a QOS Spec from a Volume Type

  1. As an administrator in the dashboard, select Admin > Volumes > Volume Types.
  2. In the Volume Types table, select the type’s Manage QOS Spec Association action.
  3. Select None from the QOS Spec to be associated list.
  4. Click Associate. The selected QOS Spec is no longer in the Associated QOS Spec column of the edited volume type.

2.2.6. Configure volume encryption

Volume encryption provides basic data protection in case the volume back end is either compromised or stolen. Both Compute and Block Storage services are integrated to allow instances to read access and use encrypted volumes. You must deploy the Key Manager service (barbican) to use volume encryption.

Important
  • Volume encryption is not supported on file-based volumes (such as NFS).
  • Retyping an unencrypted volume to an encrypted volume of the same size is not supported, because encrypted volumes require additional space to store encryption data. For more information about encrypting unencrypted volumes, see Encrypting unencrypted volumes.

Volume encryption is applied by using volume type. See Section 2.2.6.1, “Configure Volume Type Encryption Through the Dashboard” for information about encrypted volume types.

2.2.6.1. Configure Volume Type Encryption Through the Dashboard

To create encrypted volumes, you first need an encrypted volume type. Encrypting a volume type involves setting what provider class, cipher, and key size it should use:

  1. As an admin user in the dashboard, select Admin > Volumes > Volume Types.
  2. In the Actions column of the volume to be encrypted, select Create Encryption to launch the Create Volume Type Encryption wizard.
  3. From there, configure the Provider, Control Location, Cipher, and Key Size settings of the volume type’s encryption. The Description column describes each setting.

    Important

    The values listed below are the only supported options for Provider, Cipher, and Key Size.

    1. Enter luks for Provider.
    2. Enter aes-xts-plain64 for Cipher.
    3. Enter 256 for Key Size.
  4. Click Create Volume Type Encryption.

Once you have an encrypted volume type, you can invoke it to automatically create encrypted volumes. For more information on creating a volume type, see Section 2.2.2.2, “Create and Configure a Volume Type”. Specifically, select the encrypted volume type from the Type drop-down list in the Create Volume window (see Section 2.3, “Basic volume usage and configuration”).

To configure an encrypted volume type through the CLI, see Section 2.2.6.2, “Configure Volume Type Encryption Through the CLI”.

You can also re-configure the encryption settings of an encrypted volume type.

  1. Select Update Encryption from the Actions column of the volume type to launch the Update Volume Type Encryption wizard.
  2. In Project > Compute > Volumes, check the Encrypted column in the Volumes table to determine whether the volume is encrypted.
  3. If the volume is encrypted, click Yes in that column to view the encryption settings.

2.2.6.2. Configure Volume Type Encryption Through the CLI

To configure Block Storage volume encryption, do the following:

  1. Create a volume type:

    $ cinder type-create encrypt-type
  2. Configure the cipher, key size, control location, and provider settings:

    $ cinder encryption-type-create --cipher aes-xts-plain64 --key-size 256 --control-location front-end encrypt-type luks
  3. Create an encrypted volume:

    $ cinder --debug create 1 --volume-type encrypt-type --name DemoEncVol

2.2.6.3. Automatic deletion of volume image encryption key

The Block Storage service (cinder) creates an encryption key in the Key Management service (barbican) when it uploads an encrypted volume to the Image service (glance). This creates a 1:1 relationship between an encryption key and a stored image.

Encryption key deletion prevents unlimited resource consumption of the Key Management service. The Block Storage, Key Management, and Image services automatically manage the key for an encrypted volume, including the deletion of the key.

The Block Storage service automatically adds two properties to a volume image:

  • cinder_encryption_key_id - The identifier of the encryption key that the Key Management service stores for a specific image.
  • cinder_encryption_key_deletion_policy - The policy that tells the Image service to tell the Key Management service whether to delete the key associated with this image.
Important

The values of these properties are automatically assigned. To avoid unintentional data loss, do not adjust these values.

When you create a volume image, the Block Storage service sets the cinder_encryption_key_deletion_policy property to on_image_deletion. When you delete a volume image, the Image service deletes the corresponding encryption key if the cinder_encryption_key_deletion_policy equals on_image_deletion.

Important

Red Hat does not recommend manual manipulation of the cinder_encryption_key_id or cinder_encryption_key_deletion_policy properties. If you use the encryption key that is identified by the value of cinder_encryption_key_id for any other purpose, you risk data loss.

For additional information, refer to the Manage secrets with the OpenStack Key Manager guide.

2.2.7. Configure How Volumes are Allocated to Multiple Back Ends

If the Block Storage service is configured to use multiple back ends, you can use configured volume types to specify where a volume should be created. For details, see Section 2.3.2, “Specify back end for volume creation”.

The Block Storage service will automatically choose a back end if you do not specify one during volume creation. Block Storage sets the first defined back end as a default; this back end will be used until it runs out of space. At that point, Block Storage will set the second defined back end as a default, and so on.

If this is not suitable for your needs, you can use the filter scheduler to control how Block Storage should select back ends. This scheduler can use different filters to triage suitable back ends, such as:

AvailabilityZoneFilter
Filters out all back ends that do not meet the availability zone requirements of the requested volume.
CapacityFilter
Selects only back ends with enough space to accommodate the volume.
CapabilitiesFilter
Selects only back ends that can support any specified settings in the volume.
InstanceLocality
Configures clusters to use volumes local to the same node.

To configure the filter scheduler, add an environment file to your deployment containing:

parameter_defaults:
  ControllerExtraConfig: # 1
    cinder::config::cinder_config:
      DEFAULT/scheduler_default_filters:
        value: 'AvailabilityZoneFilter,CapacityFilter,CapabilitiesFilter,InstanceLocality'
1
You can also add the ControllerExtraConfig: hook and its nested sections to the parameter_defaults: section of an existing environment file.

2.2.8. Deploying availability zones

An availability zone is a provider-specific method of grouping cloud instances and services. Director uses CinderXXXAvailabilityZone parameters (where XXX is associated with a specific back end) to configure different availability zones for Block Storage volume back ends.

Procedure

To deploy different availability zones for Block Storage volume back ends:

  1. Add the following parameters to the environment file to create two availability zones:

    parameter_defaults:
     CinderXXXAvailabilityZone: zone1
     CinderYYYAvailabilityZone: zone2

    Replace XXX and YYY with supported back-end values, such as:

    CinderISCSIAvailabilityZone
    CinderNfsAvailabilityZone
    CinderRbdAvailabilityZone
    Note

    Search the /usr/share/openstack-tripleo-heat-templates/deployment/cinder/ directory for the heat template associated with your back end for the correct back-end value.

    The following example deploys two back ends where rbd is zone 1 and iSCSI is zone 2:

    parameter_defaults:
     CinderRbdAvailabilityZone: zone1
     CinderISCSIAvailabilityZone: zone2
  2. Deploy the overcloud and include the updated environment file.

2.2.9. Configure and use consistency groups

You can use the Block Storage (cinder) service to set consistency groups to group multiple volumes together as a single entity. This means that you can perform operations on multiple volumes at the same time instead of individually. You can use consistency groups to create snapshots for multiple volumes simultaneously. This also means that you can restore or clone those volumes simultaneously.

A volume can be a member of multiple consistency groups. However, you cannot delete, retype, or migrate volumes after you add them to a consistency group.

2.2.9.1. Configure consistency groups

By default, Block Storage security policy disables consistency groups APIs. You must enable it here before you use the feature. The related consistency group entries in the /etc/cinder/policy.json file of the node that hosts the Block Storage API service, openstack-cinder-api list the default settings:

"consistencygroup:create" : "group:nobody",
"consistencygroup:delete": "group:nobody",
"consistencygroup:update": "group:nobody",
"consistencygroup:get": "group:nobody",
"consistencygroup:get_all": "group:nobody",
"consistencygroup:create_cgsnapshot" : "group:nobody",
"consistencygroup:delete_cgsnapshot": "group:nobody",
"consistencygroup:get_cgsnapshot": "group:nobody",
"consistencygroup:get_all_cgsnapshots": "group:nobody",

You must change these settings in an environment file and then deploy them to the overcloud by using the openstack overcloud deploy command. Do not edit the JSON file directly because the changes are overwritten next time the overcloud is deployed.

Procedure

  1. Edit an environment file and add a new entry to the parameter_defaults section. This ensures that the entries are updated in the containers and are retained whenever the environment is re-deployed by director with the openstack overcloud deploy command.
  2. Add a new section to an environment file using CinderApiPolicies to set the consistency group settings. The equivalent parameter_defaults section with the default settings from the JSON file appear in the following way:

    parameter_defaults:
      CinderApiPolicies: { \
         cinder-consistencygroup_create: { key: 'consistencygroup:create', value: 'group:nobody' }, \
         cinder-consistencygroup_delete: { key: 'consistencygroup:delete', value: 'group:nobody' },  \
         cinder-consistencygroup_update: { key: 'consistencygroup:update', value: 'group:nobody' }, \
         cinder-consistencygroup_get: { key: 'consistencygroup:get', value: 'group:nobody' }, \
         cinder-consistencygroup_get_all: { key: 'consistencygroup:get_all', value: 'group:nobody' }, \
         cinder-consistencygroup_create_cgsnapshot: { key: 'consistencygroup:create_cgsnapshot', value: 'group:nobody' }, \
         cinder-consistencygroup_delete_cgsnapshot: { key: 'consistencygroup:delete_cgsnapshot', value: 'group:nobody' }, \
         cinder-consistencygroup_get_cgsnapshot: { key: 'consistencygroup:get_cgsnapshot', value: 'group:nobody' }, \
         cinder-consistencygroup_get_all_cgsnapshots: { key: 'consistencygroup:get_all_cgsnapshots', value: 'group:nobody' }, \
     }
  3. The value ‘group:nobody’ determines that no group can use this feature so it is effectively disabled. To enable it, change the group to another value.
  4. For increased security, set the permissions for both consistency group API and volume type management API to be identical. The volume type management API is set to "rule:admin_or_owner" by default in the same /etc/cinder/policy.json_ file:

    "volume_extension:types_manage": "rule:admin_or_owner",
  5. To make the consistency groups feature available to all users, set the API policy entries to allow users to create, use, and manage their own consistency groups. To do so, use rule:admin_or_owner:

    CinderApiPolicies: { \
         cinder-consistencygroup_create: { key: 'consistencygroup:create', value: 'rule:admin_or_owner' }, \
         cinder-consistencygroup_delete: { key: 'consistencygroup:delete', value: 'rule:admin_or_owner' },  \
         cinder-consistencygroup_update: { key: 'consistencygroup:update', value: 'rule:admin_or_owner' }, \
         cinder-consistencygroup_get: { key: 'consistencygroup:get', value: 'rule:admin_or_owner' }, \
         cinder-consistencygroup_get_all: { key: 'consistencygroup:get_all', value: 'rule:admin_or_owner' }, \
         cinder-consistencygroup_create_cgsnapshot: { key: 'consistencygroup:create_cgsnapshot', value: 'rule:admin_or_owner' }, \
         cinder-consistencygroup_delete_cgsnapshot: { key: 'consistencygroup:delete_cgsnapshot', value: 'rule:admin_or_owner' }, \
         cinder-consistencygroup_get_cgsnapshot: { key: 'consistencygroup:get_cgsnapshot', value: 'rule:admin_or_owner' }, \
         cinder-consistencygroup_get_all_cgsnapshots: { key: 'consistencygroup:get_all_cgsnapshots', value: 'rule:admin_or_owner’ }, \
     }
  6. When you have created the environment file in /home/stack/templates/, log in as the stack user and deploy the configuration:

    $ openstack overcloud deploy --templates \
    -e /home/stack/templates/<ENV_FILE>.yaml

    Replace <ENV_FILE.yaml> with the name of the file with the ExtraConfig settings you added.

    Important

    If you passed any extra environment files when you created the overcloud, pass them again here by using the -e option to avoid making undesired changes to the overcloud.

For more information about the openstack overcloud deploy command, see Creating the Overcloud with the CLI Tools in the Director Installation and Usage guide.

2.2.9.2. Creating consistency groups

After you enable the consistency groups API, you can start creating consistency groups.

Procedure

  1. As an admin user in the dashboard, select Project > Compute > Volumes > Volume Consistency Groups.
  2. Click Create Consistency Group.
  3. In the Consistency Group Information tab of the wizard, enter a name and description for your consistency group. Then, specify its Availability Zone.
  4. You can also add volume types to your consistency group. When you create volumes within the consistency group, the Block Storage service will apply compatible settings from those volume types. To add a volume type, click its + button from the All available volume types list.
  5. Click Create Consistency Group. It appears next in the Volume Consistency Groups table.

2.2.9.3. Managing consistency groups

Procedure

  1. Optional: You can change the name or description of a consistency group by selecting Edit Consistency Group from its Action column.
  2. To add or remove volumes from a consistency group directly, as an admin user in the dashboard, select Project > Compute > Volumes > Volume Consistency Groups.
  3. Find the consistency group you want to configure. In the Actions column of that consistency group, select Manage Volumes. This launches the Add/Remove Consistency Group Volumes wizard.

    1. To add a volume to the consistency group, click its + button from the All available volumes list.
    2. To remove a volume from the consistency group, click its - button from the Selected volumes list.
  4. Click Edit Consistency Group.

2.2.9.4. Create and manage consistency group snapshots

After you add volumes to a consistency group, you can now create snapshots from it.

Procedure

  1. Log in as admin user from the command line on the node that hosts the openstack-cinder-api and enter:

    # export OS_VOLUME_API_VERSION=2

    This configures the client to use version 2 of the openstack-cinder-api.

  2. List all available consistency groups and their respective IDs:

    # cinder consisgroup-list
  3. Create snapshots using the consistency group:

    # cinder cgsnapshot-create --name <CGSNAPNAME> --description "<DESCRIPTION>" <CGNAMEID>

    Replace:

    • <CGSNAPNAME> with the name of the snapshot (optional).
    • <DESCRIPTION> with a description of the snapshot (optional).
    • <CGNAMEID> with the name or ID of the consistency group.
  4. Display a list of all available consistency group snapshots:

    # cinder cgsnapshot-list

2.2.9.5. Clone consistency groups

You can also use consistency groups to create a whole batch of pre-configured volumes simultaneously. You can do this by cloning an existing consistency group or restoring a consistency group snapshot. Both processes use the same command.

Procedure

  1. To clone an existing consistency group:

    # cinder consisgroup-create-from-src --source-cg <CGNAMEID> --name <CGNAME> --description "<DESCRIPTION>"

    Replace:

    • <CGNAMEID> is the name or ID of the consistency group you want to clone.
    • <CGNAME> is the name of your consistency group (optional).
    • <DESCRIPTION> is a description of your consistency group (optional).
  2. To create a consistency group from a consistency group snapshot:

    # cinder consisgroup-create-from-src --cgsnapshot <CGSNAPNAME> --name <CGNAME> --description "<DESCRIPTION>

    Replace <CGSNAPNAME> with the name or ID of the snapshot you are using to create the consistency group.

2.3. Basic volume usage and configuration

The following procedures describe how to perform basic end-user volume management. These procedures do not require administrative privileges.

Important

You must install host bus adapters (HBAs) on all Controller nodes and Compute nodes in any deployment that uses the Block Storage service (cinder) and a Fibre Channel (FC) back end.

2.3.1. Create a volume

Important

The default maximum number of volumes you can create for a project is 10.

Procedure

  1. In the dashboard, select Project > Compute > Volumes.
  2. Click Create Volume, and edit the following fields:

    FieldDescription

    Volume name

    Name of the volume.

    Description

    Optional, short description of the volume.

    Type

    Optional volume type (see Section 2.2.2, “Group Volume Settings with Volume Types”).

    If you have multiple Block Storage back ends, you can use this to select a specific back end. See Section 2.3.2, “Specify back end for volume creation”.

    Size (GB)

    Volume size (in gigabytes). If you want to create an encrypted volume from an unencrypted image, you must ensure that the volume size is at least 1GB larger than the image size so that the encryption data does not truncate the volume data.

    Availability Zone

    Availability zones (logical server groups), along with host aggregates, are a common method for segregating resources within OpenStack. Availability zones are defined during installation. For more information about availability zones and host aggregates, see Creating and managing host aggregates.

  3. Specify a Volume Source:

    SourceDescription

    No source, empty volume

    The volume is empty and does not contain a file system or partition table.

    Snapshot

    Use an existing snapshot as a volume source. If you select this option, a new Use snapshot as a source list opens; you can then choose a snapshot from the list. If you want to create a new volume from a snapshot of an encrypted volume, you must ensure that the new volume is at least 1GB larger than the old volume. For more information about volume snapshots, see Section 2.3.10, “Create, use, or delete volume snapshots”.

    Image

    Use an existing image as a volume source. If you select this option, a new Use snapshot as a source list opens; you can then choose an image from the list.

    Volume

    Use an existing volume as a volume source. If you select this option, a new Use snapshot as a source list opens; you can then choose a volume from the list.

  4. Click Create Volume. After the volume is created, its name appears in the Volumes table.

You can also change the volume type later on. For more information, see Section 2.3.16, “Volume retyping”.

2.3.2. Specify back end for volume creation

Whenever multiple Block Storage (cinder) back ends are configured, you must also create a volume type for each back end. You can then use the type to specify which back end to use for a created volume. For more information about volume types, see Section 2.2.2, “Group Volume Settings with Volume Types”.

To specify a back end when creating a volume, select its corresponding volume type from the Type list (see Section 2.3.1, “Create a volume”).

If you do not specify a back end during volume creation, the Block Storage service automatically chooses one for you. By default, the service chooses the back end with the most available free space. You can also configure the Block Storage service to choose randomly among all available back ends instead. For more information, see Section 2.2.7, “Configure How Volumes are Allocated to Multiple Back Ends”.

2.3.3. Edit a volume name or description

  1. In the dashboard, select Project > Compute > Volumes.
  2. Select the volume’s Edit Volume button.
  3. Edit the volume name or description as required.
  4. Click Edit Volume to save your changes.
Note

To create an encrypted volume, you must first have a volume type configured specifically for volume encryption. In addition, you must configure both Compute and Block Storage services to use the same static key. For information about how to set up the requirements for volume encryption, see Section 2.2.6, “Configure volume encryption”.

2.3.4. Resize (extend) a volume

Note

The ability to resize a volume in use is supported but is driver dependant. RBD is supported. You cannot extend in-use multi-attach volumes. For more information about support for this feature, contact Red Hat Support.

  1. List the volumes to retrieve the ID of the volume you want to extend:

    $ cinder list
  2. To resize the volume, run the following commands to specify the correct API microversion, then pass the volume ID and the new size (a value greater than the old size) as parameters:

    $ OS_VOLUME_API_VERSION=<API microversion>
    $ cinder extend <volume ID> <size>

    Replace <API_microversion>, <volume_ID>, and <size> with appropriate values, for example:

    $ OS_VOLUME_API_VERSION=3.42
    $ cinder extend 573e024d-5235-49ce-8332-be1576d323f8 10

2.3.5. Delete a volume

  1. In the dashboard, select Project > Compute > Volumes.
  2. In the Volumes table, select the volume to delete.
  3. Click Delete Volumes.
Note

A volume cannot be deleted if it has existing snapshots. For instructions on how to delete snapshots, see Section 2.3.10, “Create, use, or delete volume snapshots”.

2.3.6. Attach and detach a volume to an instance

Instances can use a volume for persistent storage. A volume can only be attached to one instance at a time. For more information, see Attaching a volume to an instance in the Creating and Managing Instances guide.

2.3.6.1. Attaching a volume to an instance

  1. In the dashboard, select Project > Compute > Volumes.
  2. Select the Edit Attachments action. If the volume is not attached to an instance, the Attach To Instance drop-down list is visible.
  3. From the Attach To Instance list, select the instance to which you want to attach the volume.
  4. Click Attach Volume.

2.3.6.2. Detaching a volume from an instance

  1. In the dashboard, select Project > Compute > Volumes.
  2. Select the volume’s Manage Attachments action. If the volume is attached to an instance, the instance’s name is displayed in the Attachments table.
  3. Click Detach Volume in this and the next dialog screen.

2.3.7. Attach a volume to multiple instances

Volume multi-attach gives multiple instances simultaneous read/write access to a Block Storage volume. This feature works when you use Ceph as a Block Storage (cinder) back end. The Ceph RBD driver is supported.

Warning

You must use a multi-attach or cluster-aware file system to manage write operations from multiple instances. Failure to do so causes data corruption.

Warning

To use the optional multi-attach feature, your cinder driver must support it. For more information about the certification for your vendor plugin, see the following locations:

Contact Red Hat support to verify that multi-attach is supported for your vendor plugin.

Warning

Restrictions for multi-attach volumes:

  • Live migration of multi-attach volumes is not available.
  • Volume encryption is not supported with multi-attach volumes.
  • Retyping an attached volume from a multi-attach type to non-multi-attach type or non-multi-attach to multi-attach is not possible.
  • Read-only multi-attach is not supported.

2.3.7.1. Creating a multi-attach volume type

To attach a volume to multiple instances, set the multiattach flag to <is>True in the volume extra specs. When you create a multi-attach volume type, the volume inherits the flag and becomes a multi-attach volume.

Note

By default, creating a new volume type is an admin-only operation.

Procedure

  1. Run the following commands to create a multi-attach volume type:

    $ cinder type-create multiattach
    $ cinder type-key multiattach set multiattach="<is> True"
    Note

    This procedure creates a volume on any back end that supports multiattach. Therefore, if there are two back ends that support multiattach, the scheduler decides which back end to use based on the available space at the time of creation.

  2. Run the following command to specify the back end:

    $ cinder type-key multiattach set volume_backend_name=<backend_name>

2.3.7.2. Volume retyping

You can retype a volume to be multi-attach capable or retype a multi-attach capable volume to make it incapable of attaching to multiple instances. However, you can retype a volume only when it is not in use and its status is available.

When you attach a multi-attach volume, some hypervisors require special considerations, such as when you disable caching. Currently, there is no way to safely update an attached volume while keeping it attached the entire time. Retyping fails if you attempt to retype a volume that is attached to multiple instances.

2.3.7.3. Creating a multi-attach volume

After you create a multi-attach volume type, create a multi-attach volume.

Procedure

  1. Run the following command to create a multi-attach volume:

    $ cinder create <volume_size> --name <volume_name> --volume-type multiattach
  2. Run the following command to verify that a volume is multi-attach capable. If the volume is multi-attach capable, the multiattach field equals True.

    $ cinder show <vol_id> | grep multiattach
    
    | multiattach | True |

You can now attach the volume to multiple instances. For information about how to attach a volume to an instance, see Attach a volume to an instance.

2.3.7.4. Supported back ends

The Block Storage back end must support multi-attach. For information about supported back ends, contact Red Hat Support.

2.3.8. Read-only volumes

A volume can be marked read-only to protect its data from being accidentally overwritten or deleted. To do so, set the volume to read-only by using the following command:

# cinder readonly-mode-update <VOLUME-ID> true

To set a read-only volume back to read-write, run:

# cinder readonly-mode-update <VOLUME-ID> false

2.3.9. Change a volume owner

To change the owner of a volume, you must perform a volume transfer. A volume transfer is initiated by the volume owner, and the change in ownership is complete after the transfer is accepted by the new owner.

2.3.9.1. Transfer a volume from the command line

  1. Log in as the volume’s current owner.
  2. List the available volumes:

    # cinder list
  3. Initiate the volume transfer:

    # cinder transfer-create VOLUME

    Where VOLUME is the name or ID of the volume you wish to transfer. For example,

      +------------+--------------------------------------+
      |  Property  |                Value                 |
      +------------+--------------------------------------+
      |  auth_key  |           f03bf51ce7ead189           |
      | created_at |      2014-12-08T03:46:31.884066      |
      |     id     | 3f5dc551-c675-4205-a13a-d30f88527490 |
      |    name    |                 None                 |
      | volume_id  | bcf7d015-4843-464c-880d-7376851ca728 |
      +------------+--------------------------------------+

    The cinder transfer-create command clears the ownership of the volume and creates an id and auth_key for the transfer. These values can be given to, and used by, another user to accept the transfer and become the new owner of the volume.

  4. The new user can now claim ownership of the volume. To do so, the user should first log in from the command line and run:

    # cinder transfer-accept TRANSFERID TRANSFERKEY

    Where TRANSFERID and TRANSFERKEY are the id and auth_key values returned by the cinder transfer-create command, respectively. For example,

    # cinder transfer-accept 3f5dc551-c675-4205-a13a-d30f88527490 f03bf51ce7ead189
Note

You can view all available volume transfers using:

# cinder transfer-list

2.3.9.2. Transfer a volume by using the dashboard

Create a volume transfer from the dashboard

  1. As the volume owner in the dashboard, select Projects > Volumes.
  2. In the Actions column of the volume to transfer, select Create Transfer.
  3. In the Create Transfer dialog box, enter a name for the transfer and click Create Volume Transfer.

    The volume transfer is created, and in the Volume Transfer screen you can capture the transfer ID and the authorization key to send to the recipient project.

    Click the Download transfer credentials button to download a .txt file containing the transfer name, transfer ID, and authorization key.

    Note

    The authorization key is available only in the Volume Transfer screen. If you lose the authorization key, you must cancel the transfer and create another transfer to generate a new authorization key.

  4. Close the Volume Transfer screen to return to the volume list.

    The volume status changes to awaiting-transfer until the recipient project accepts the transfer

Accept a volume transfer from the dashboard

  1. As the recipient project owner in the dashboard, select Projects > Volumes.
  2. Click Accept Transfer.
  3. In the Accept Volume Transfer dialog box, enter the transfer ID and the authorization key that you received from the volume owner and click Accept Volume Transfer.

    The volume now appears in the volume list for the active project.

2.3.10. Create, use, or delete volume snapshots

You can preserve the state of a volume at a specific point in time by creating a volume snapshot. You can then use the snapshot to clone new volumes.

Note

Volume backups are different from snapshots. Backups preserve the data contained in the volume, whereas snapshots preserve the state of a volume at a specific point in time. You cannot delete a volume if it has existing snapshots. Volume backups prevent data loss, whereas snapshots facilitate cloning.

For this reason, snapshot back ends are typically colocated with volume back ends to minimize latency during cloning. By contrast, a backup repository is usually located in a different location, for example, on a different node, physical storage, or even geographical location in a typical enterprise deployment. This is to protect the backup repository from any damage that might occur to the volume back end.

For more information about volume backups, see the Block Storage Backup Guide.

To create a volume snapshot:

  1. In the dashboard, select Project > Compute > Volumes.
  2. Select the Create Snapshot action of the target volume.
  3. Provide a Snapshot Name for the snapshot and click Create a Volume Snapshot. The Volume Snapshots tab displays all snapshots.

You can clone new volumes from a snapshot when it appears in the Volume Snapshots table. Select the Create Volume action of the snapshot. For more information about volume creation, see Section 2.3.1, “Create a volume”.

Important

If you want to create a new volume from a snapshot of an encrypted volume, ensure that the new volume is at least 1GB larger than the old volume.

To delete a snapshot, select its Delete Volume Snapshot action.

If your OpenStack deployment uses a Red Hat Ceph back end, see Section 2.3.10.1, “Protected and unprotected snapshots in a Red Hat Ceph Storage back end” for more information about snapshot security and troubleshooting.

Note

For RADOS block device (RBD) volumes for the Block Storage service (cinder) that are created from snapshots, you can use the CinderRbdFlattenVolumeFromSnapshot heat parameter to flatten and remove the dependency on the snapshot. When you set CinderRbdFlattenVolumeFromSnapshot to true, the Block Storage service flattens RBD volumes and removes the dependency on the snapshot and also flattens all future snapshots. The default value is false, which is also the default value for the cinder RBD driver.

Be aware that flattening a snapshot removes any potential block sharing with the parent and results in larger snapshot sizes on the back end and increases the time for snapshot creation.

2.3.10.1. Protected and unprotected snapshots in a Red Hat Ceph Storage back end

When using Red Hat Ceph Storage as a back end for your OpenStack deployment, you can set a snapshot to protected in the back end. Attempting to delete protected snapshots through OpenStack (as in, through the dashboard or the cinder snapshot-delete command) will fail.

When this occurs, set the snapshot to unprotected in the Red Hat Ceph back end first. Afterwards, you should be able to delete the snapshot through OpenStack as normal.

For related instructions, see Protecting a Snapshot and Unprotecting a Snapshot.

2.3.11. Use a snapshot to restore to the last state of a volume

You can recover the most recent snapshot of a volume. This means that you can perform an in-place revert of the volume data to its most recent snapshot.

Warning
The ability to recover the most recent snapshot of a volume is supported but is driver dependent. The correct implementation of this feature is driver assisted. For more information about support for this feature, contact your driver vendor.

Limitations

  • There might be limitations to using the revert-to-snapshot feature with multi-attach volumes. Check whether such limitations apply before you use this feature.
  • You cannot revert a volume that you resize (extend) after you take a snapshot.
  • You cannot use the revert-to-snapshot feature on an attached or in-use volume.

Prerequisites

  • Block Storage (cinder) API microversion 3.40 or later.
  • You must have created at least one snapshot for the volume.

Procedure

  1. Log in to the undercloud as the stack user.
  2. Source the overcloudrc file:

    [stack@undercloud ~] $ source overcloudrc
  3. Detach your volume:

    $ nova volume-detach <instance_id> <vol_id>

    Replace <instance_id> and <vol_id> with the IDs of the instance and volume that you want to revert.

  4. Locate the ID or name of the snapshot that you want to revert. You can only revert the latest snapshot.

    $ cinder snapshot-list
  5. Revert the snapshot:

    $ cinder --os-volume-api-version=3.40 revert-to-snapshot  <snapshot_id or snapshot_name>

    Replace <snapshot_id or snapshot_name> with the ID or the name of the snapshot.

  6. Optional: You can use the cinder snapshot-list command to check that the volume you are reverting is in a reverting state.

    $  cinder snapshot-list
  7. Reattach the volume:

    $  nova volume-attach <instance_id> <vol_id>

    Replace <instance_id> and <vol_id> with the IDs of the instance and volume that you reverted.

2.3.11.1. Verifying that your revert is successful

Procedure

  • To check that the procedure is successful, you can use the cinder list command to verify that the volume you reverted is now in the available state.

    $ cinder list
    Note
    If you used Block Storage (cinder) as a bootable root volume, you cannot use the revert-to-snapshot feature on that volume because it is not in the available state. To use this feature, the instance must have been booted with the delete_on_termination=false (default) property to preserve the boot volume if the instance is terminated. When you want to revert to a snapshot, you must first delete the initial instance so that the volume is available. You can then revert it and create a new instance from the volume.

2.3.12. Upload a volume to the Image Service

You can upload an existing volume as an image to the Image service directly. To do so:

  1. In the dashboard, select Project > Compute > Volumes.
  2. Select the target volume’s Upload to Image action.
  3. Provide an Image Name for the volume and select a Disk Format from the list.
  4. Click Upload.

To view the uploaded image, select Project > Compute > Images. The new image appears in the Images table. For information on how to use and configure images, see Manage images in the Creating and Managing Images guide.

2.3.13. Moving volumes between back ends

There are many reasons to move volumes from one storage back end to another, such as:

  • To retire storage systems that are no longer supported.
  • To change the storage class or tier of a volume.
  • To change the availability zone of a volume.

With the Block Storage service (cinder), you can move volumes between back ends in the following ways:

  • Retype: The default policy allows volume owners and administrators to retype a volume. The retype operation is the most common way to move volumes between back ends.
  • Migrate: The default policy allows only administrators to migrate a volume. Volume migration is reserved for specific use cases, because it is restrictive and requires a clear understanding about how deployments work. For more information, see Migrate a volume.

Restrictions

Red Hat supports moving volumes between back ends within and across availability zones (AZs), but with the following restrictions:

  • Volumes must have either available or in-use status to move.
  • Support for in-use volumes is driver dependent.
  • Volumes cannot have snapshots.
  • Volumes cannot belong to a group or consistency group.

2.3.14. Moving available volumes

You can move available volumes between all back ends, but performance depends on the back ends that you use. Many back ends support assisted migration. For more information about back end support for assisted migration, contact the vendor.

Assisted migration works with both volume retype and volume migration. With assisted migration, the back end optimizes the movement of the data from the source back end to the destination back end, but both back ends must be from the same vendor.

Note

Red Hat supports back end-assisted migrations only with multi-pool back ends or when you use the cinder migrate operation for single-pool back ends, such as RBD.

2.3.14.1. Generic volume migration

When assisted migrations between back ends are not possible, the Block Storage service performs a generic volume migration.

Generic volume migration requires volumes on both back ends to be connected before the Block Storage (cinder) service moves data from the source volume to the Controller node and from the Controller node to the destination volume. The Block Storage service seamlessly performs the process regardless of the type of storage from the source and destination back ends.

Important

Ensure that you have adequate bandwidth before you perform a generic volume migration. The duration of a generic volume migration is directly proportional to the size of the volume, which makes the operation slower than assisted migration.

2.3.15. Moving in-use volumes

There is no optimized or assisted option for moving in-use volumes. When you move in-use volumes, the Compute service (nova) must use the hypervisor to transfer data from a volume in the source back end to a volume in the destination back end. This requires coordination with the hypervisor that runs the instance where the volume is in use.

The Block Storage service (cinder) and the Compute service work together to perform this operation. The Compute service manages most of the work, because the data is copied from one volume to another through the Compute node.

Important

Ensure that you have adequate bandwidth before you move in-use volumes. The duration of this operation is directly proportional to the size of the volume, which makes the operation slower than assisted migration.

Restrictions

  • In-use multi-attach volumes cannot be moved while they are attached to more than one nova instance.
  • Non block devices are not supported, which limits storage protocols on the target back end to be iSCSI, Fibre Channel (FC), or RBD.

2.3.16. Volume retyping

Volume retyping is the standard way to move volumes from one back end to another. The operation requires the administrator to define the appropriate volume types for the different back ends. The default policy allows volume owners and administrators to retype volumes.

When you retype a volume, you apply a volume type and its settings to an already existing volume. For more information about volume types, see Section 2.2.2, “Group Volume Settings with Volume Types”.

You can retype a volume provided that the extra specs of the new volume type can be applied to the existing volume. You can retype a volume to apply pre-defined settings or storage attributes to an existing volume, such as:

  • To move the volume to a different back end.
  • To change the storage class or tier of a volume.
  • To enable or disable features such as replication.

Retyping a volume does not necessarily mean that you must move the volume from one back end to another. However, there are circumstances in which you must move a volume to complete a retype:

  • The new volume type has a different volume_backend_name defined.
  • The volume_backend_name of the current volume type is undefined, and the volume is stored in a different back end than the one specified by the volume_backend_name of the new volume type.

Moving a volume from one back end to another can require extensive time and resources. Therefore, when a retype requires moving data, the Block Storage service does not move data by default. The operation fails unless it is explicitly allowed by specifying a migration policy as part of the retype request. For more information, see Section 2.3.16.2, “Retyping a volume from the command line”.

Restrictions

  • You cannot retype all volumes. For more information about moving volumes between back ends, see Section 2.3.13, “Moving volumes between back ends”.
  • You cannot retype unencrypted volumes to be encrypted volume types, but you can retype encrypted volumes to be unencrypted.
  • Users with no administrative privileges can only retype volumes that they own.

2.3.16.1. Retyping a volume from the dashboard UI

Use the dashboard UI to retype a volume.

Procedure

  1. In the dashboard, select Project > Compute > Volumes.
  2. In the Actions column of the volume you want to migrate, select Change Volume Type.
  3. In the Change Volume Type dialog, select the target volume type and define the new back end from the Type list.
  4. If you are migrating the volume to another back end, select On Demand from the Migration Policy list. For more information, see Section 2.3.13, “Moving volumes between back ends”.
  5. Click Change Volume Type to start the migration.

2.3.16.2. Retyping a volume from the command line

Similar to the dashboard UI procedure, you can retype a volume from the command line.

Procedure

  1. Enter the following command to retype a volume:

    $ cinder retype <volume id> <new volume type name>
  2. If the retype operation requires moving the volume from one back end to another, the Block Storage service requires a specific flag:

    $ cinder retype --migration-policy on-demand <volume id> <new volume type name>
    Note

    As the retype operation progresses, the volume status changes to retyping.

  3. Enter the following command and review the volume_type field to confirm that the retype operation succeeded. The volume_type field shows the new volume type.

    $ cinder show <volume id>
    Note

    When you initiate a retype operation, the volume name is duplicated. If you enter the cinder show command with the volume name, the cinder client will return an error similar to ERROR: Multiple volume matches found for '<volume name>'. To avoid this error, use the volume ID instead.

2.3.17. Enabling LVM2 filtering on overcloud nodes

If you use LVM2 (Logical Volume Management) volumes with certain Block Storage service (cinder) back ends, the volumes that you create inside Red Hat OpenStack Platform (RHOSP) guests might become visible on the overcloud nodes that host cinder-volume or nova-compute containers. In this case, the LVM2 tools on the host scan the LVM2 volumes that the OpenStack guest creates, which can result in one or more of the following problems on Compute or Controller nodes:

  • LVM appears to see volume groups from guests
  • LVM reports duplicate volume group names
  • Volume detachments fail because LVM is accessing the storage
  • Guests fail to boot due to problems with LVM
  • The LVM on the guest machine is in a partial state due to a missing disk that actually exists
  • Block Storage service (cinder) actions fail on devices that have LVM
  • Block Storage service (cinder) snapshots fail to remove correctly
  • Errors during live migration: /etc/multipath.conf does not exist

To prevent this erroneous scanning, and to segregate guest LVM2 volumes from the host node, you can enable and configure a filter with the LVMFilterEnabled heat parameter when you deploy or update the overcloud. This filter is computed from the list of physical devices that host active LVM2 volumes. You can also allow and deny block devices explicitly with the LVMFilterAllowlist and LVMFilterDenylist parameters. You can apply this filtering globally, to specific node roles, or to specific devices.

Note

This feature is available in this release as a Technology Preview, and therefore is not fully supported by Red Hat. It should only be used for testing, and should not be deployed in a production environment. For more information about Technology Preview features, see Scope of Coverage Details.

Prerequisites

Procedure

  1. Log in to the undercloud host as the stack user.
  2. Source the undercloud credentials file:

    $ source ~/stackrc
  3. Create a new environment file, or modify an existing environment file. In this example, create a new file lvm2-filtering.yaml:

    $ touch ~/lvm2-filtering.yaml
  4. Include the following parameter in the environment file:

    parameter_defaults:
      LVMFilterEnabled: true

    You can further customize the implementation of the LVM2 filter. For example, to enable filtering only on Compute nodes, use the following configuration:

    parameter_defaults:
      ComputeParameters:
        LVMFilterEnabled: true

    These parameters also support regular expression. To enable filtering only on Compute nodes, and ignore all devices that start with /dev/sd, use the following configuration:

    parameter_defaults:
      ComputeParameters:
        LVMFilterEnabled: true
        LVMFilterDenylist:
          - /dev/sd.*
  5. Run the openstack overcloud deploy command and include the environment file that contains the LVM2 filtering configuration, as well as any other environment files that are relevant to your overcloud deployment:

    $ openstack overcloud deploy --templates \
    <environment-files> \
    -e lvm2-filtering.yaml

2.4. Advanced Volume Configuration

The following procedures describe how to perform advanced volume management procedures.

Important

You must install host bus adapters (HBAs) on all Controller nodes and Compute nodes in any deployment that uses the Block Storage service (cinder) and a Fibre Channel (FC) back end.

2.4.1. Migrate a Volume

With the Block Storage service (cinder) you can migrate volumes between back ends within and across availability zones (AZs). This is the least common way to move volumes from one back end to another. The default policy allows only administrators to migrate volumes. Do not change the default policy.

In highly customized deployments or in situations in which you must retire a storage system, an administrator can migrate volumes. In both use cases, multiple storage systems share the same volume_backend_name, or it is undefined.

Restrictions

  • The volume cannot be replicated.
  • The destination back end must be different from the current back end of the volume.
  • The existing volume type must be valid for the new back end, which means the following must be true:

    • Volume type must not have the backend_volume_name defined in its extra specs, or both Block Storage back ends must be configured with the same backend_volume_name.
    • Both back ends must support the same features configured in the volume type, such as support for thin provisioning, support for thick provisioning, or other feature configurations.
Note

Moving volumes from one back end to another might require extensive time and resources. For more information, see Section 2.3.13, “Moving volumes between back ends”.

2.4.1.1. Migrate between back ends

Use the dashboard UI to migrate a volume between back ends.

Procedure

  1. In the dashboard, select Admin > Volumes.
  2. In the Actions column of the volume you want to migrate, select Migrate Volume.
  3. In the Migrate Volume dialog, select the target host from the Destination Host drop-down list.

    Note

    To bypass any driver optimizations for the host migration, select the Force Host Copy check box.

  4. Click Migrate to start the migration.

2.4.1.2. Migrating between back ends from the command line

Administrators can use the command line to migrate volumes between back ends.

Procedure

  1. Enter the following command to retrieve the name of the destination back end:

    $ cinder get-pools --detail
    
    Property                      | Value
    
    ...
    
    | name                        | localdomain@lvmdriver-1#lvmdriver-1
    | pool_name                   | lvmdriver-1
    
    ...
    
    | volume_backend_name         | lvmdriver-1
    
    ...
    
    Property                      | Value
    
    ...
                                                          |
    | name                        | localdomain@lvmdriver-2#lvmdriver-1
    | pool_name                   | lvmdriver-1
    
    ...
    
    | volume_backend_name         | lvmdriver-1
    
    ...

    The back end names take the form host@volume_backend_name#pool.

    In the example output, there are two LVM back ends exposed in the Block Storage service: localdomain@lvmdriver-1#lvmdriver-1 and localdomain@lvmdriver-2#lvmdriver-1. Notice that both back ends share the same volume_backend_name, lvmdriver-1.

    Note

    Use of LVM is for example only. LVM is not supported in production environments.

  2. Enter the following command to migrate a volume from one back end to another:

    $ cinder migrate <volume id or name> <new host>

2.4.1.3. Verifying volume migration

When you create a volume, the migration_status value equals None. When you initiate the migration, the status changes to migrating. When the migration completes, the status changes to either success or error.

After the Block Storage service accepts the migration request, the cinder client responds with a message similar to Request to migrate volume <volume id> has been accepted. However, it takes time for the migration to complete. As an administrator, you can verify the status of the migration.

Procedure

  1. Enter the following command and review the migration_status field:

    $ cinder show <volume id>
    Note

    When you initiate a generic volume migration, the volume name is duplicated. If you enter the cinder show command with the volume name, the cinder client returns an error similar to ERROR: Multiple volume matches found for '<volume name>'. To avoid this error, use the volume ID instead.

After a successful migration, the host field matches the <new host> value set in the cinder migrate command.

2.4.2. Encrypting unencrypted volumes

To encrypt an unencrypted volume, you must either back up the unencrypted volume and then restore it to a new encrypted volume, or create an Image service (glance) image from the unencrypted volume and then create a new encrypted volume from the image.

Prerequisites

  • An unencrypted volume that you want to encrypt.

Procedure

  1. If the cinder-backup service is available, back up the current unencrypted volume:

    $ cinder backup-create <unencrypted_volume>
    • Replace <unencrypted_volume> with the name or ID of the unencrypted volume.
  2. Create a new encrypted volume:

    $ cinder create <encrypted_volume_size> --volume-type <encrypted_volume_type>
    • Replace <encrypted_volume_size> with the size of the new volume in GB. This value must be larger than the size of the unencrypted volume by 1GB to accommodate the encryption metadata.
    • Replace <encrypted_volume_type> with the encryption type that you require.
  3. Restore the backup of the unencrypted volume to the new encrypted volume:

    $ cinder backup-restore <backup> --volume <encrypted_volume>
    • Replace <backup> with the name or ID of the unencrypted volume backup.
    • Replace <encrypted_volume> with the ID of the new encrypted volume.

If the cinder-backup service is unavailable, use the upload-to-image command to create an image of the unencrypted volume, and then create a new encrypted volume from the image.

  1. Create an Image service image of the unencrypted volume:

    $ cinder upload-to-image <unencrypted_volume> <new_image>
    • Replace <unencrypted_volume> with the name or ID of the unencrypted volume.
    • Replace <new_image> with a name for the new image.
  2. Create a new volume from the image that is 1GB larger than the image:

    $ cinder volume create --size <size> --volume-type luks --image <new_image> <encrypted_volume_name>
    • Replace <size> with the size of the new volume. This value must be 1GB larger than the size of the old unencrypted volume.
    • Replace <new_image> with the name of the image that you created from the unencrypted volume.
    • Replace <encrypted_volume_name> with a name for the new encrypted volume.

2.5. Multipath configuration

Use multipath to configure multiple I/O paths between server nodes and storage arrays into a single device to create redundancy and improve performance. You can configure multipath on new and existing overcloud deployments.

Graphic depicts the logical input/output data paths of a Red Hat OpenStack Platform deployment configured using cinder multipath I/O

2.5.1. Configuring multipath on new deployments

Complete this procedure to configure multipath on a new overcloud deployment.

For information about how to configure multipath on existing overcloud deployments, see Section 2.5.2, “Configuring multipath on existing deployments”.

Prerequisites

The overcloud Controller and Compute nodes must have access to the Red Hat Enterprise Linux server repository. For more information, see Downloading the base cloud image in the Director Installation and Usage guide.

Procedure

  1. Configure the overcloud.

    Note

    For more information, see Configuring a basic overcloud with CLI tools in the Director Installation and Usage guide.

  2. Update the heat template to enable multipath:

    parameter_defaults:
      NovaLibvirtVolumeUseMultipath:  true
      NovaComputeOptVolumes:
        - /etc/multipath.conf:/etc/multipath.conf:ro
        - /etc/multipath/:/etc/multipath/:rw
      CinderVolumeOptVolumes:
        - /etc/multipath.conf:/etc/multipath.conf:ro
        - /etc/multipath/:/etc/multipath/:rw
  3. Optional: If you are using Block Storage (cinder) as an Image service (glance) back end, you must also complete the following steps:

    1. Add the following GlanceApiOptVolumes configuration to the heat template:

      parameter_defaults:
        GlanceApiOptVolumes:
          - /etc/multipath.conf:/etc/multipath.conf:ro
          - /etc/multipath/:/etc/multipath/:rw
    2. Set the ControllerExtraConfig parameter in the following way:

      parameter_defaults:
        ControllerExtraConfig:
          glance::config::api_config:
            default_backend/cinder_use_multipath:
              value: true
      Note
      Ensure that both default_backend and the GlanceBackendID heat template default value match.
  4. For every configured back end, set use_multipath_for_image_xfer to true:

    parameter_defaults:
      ExtraConfig:
        cinder::config::cinder_config:
          <backend>/use_multipath_for_image_xfer:
            value: true
  5. Deploy the overcloud:

    $ openstack overcloud deploy
    Note

    For information about creating the overcloud using overcloud parameters, see Creating the Overcloud with the CLI Tools in the Director Installation and Usage guide.

  6. Before containers are running, install multipath on all Controller and Compute nodes:

    $ sudo dnf install -y device-mapper-multipath
    Note

    Director provides a set of hooks to support custom configuration for specific node roles after the first boot completes and before the core configuration begins. For more information about custom overcloud configuration, see Pre-Configuration: Customizing Specific Overcloud Roles in the Advanced Overcloud Customization guide.

  7. Configure the multipath daemon on all Controller and Compute nodes:

    $ mpathconf --enable --with_multipathd y --user_friendly_names n --find_multipaths y
    Note

    The example code creates a basic multipath configuration that works for most environments. However, check with your storage vendor for recommendations, because some vendors have optimized configurations that are specific to their hardware. For more information about multipath, see the Configuring device mapper multipath guide.

  8. Run the following command on all Controller and Compute nodes to prevent partition creation:

    $ sed -i "s/^defaults {/defaults {\n\tskip_kpartx yes/" /etc/multipath.conf
    Note

    Setting skip_kpartx to yes prevents kpartx on the Compute node from automatically creating partitions on the device, which prevents unnecessary device mapper entries. For more information about configuration attributes, see Modifying the DM-Multipath configuration file in the Configuring device mapper multipath guide.

  9. Start the multipath daemon on all Controller and Compute nodes:

    $ systemctl enable --now multipathd

2.5.2. Configuring multipath on existing deployments

Configure multipath on existing deployments so that your workloads can use multipath functionality.

Note

Any new workloads that you create after you configure multipath on existing deployments are multipath-aware by default. If you have any pre-existing workloads, you must shelve and unshelve the instances to enable multipath on these instances.

For more information about how to configure multipath on new overcloud deployments, see Section 2.5.1, “Configuring multipath on new deployments”.

Prerequisites

The overcloud Controller and Compute nodes must have access to the Red Hat Enterprise Linux server repository. For more information, see Downloading the base cloud image in the Director Installation and Usage guide.

Procedure

  1. Verify that multipath is installed on all Controller and Compute nodes:

    $ rpm -qa | grep device-mapper-multipath
    
    device-mapper-multipath-0.4.9-127.el8.x86_64
    device-mapper-multipath-libs-0.4.9-127.el8.x86_64

    If multipath is not installed, install it on all Controller and Compute nodes:

    $ sudo dnf install -y device-mapper-multipath
  2. Configure the multipath daemon on all Controller and Compute nodes:

    $ mpathconf --enable --with_multipathd y --user_friendly_names n --find_multipaths y
    Note

    The example code creates a basic multipath configuration that works for most environments. However, check with your storage vendor for recommendations, because some vendors have optimized configurations specific to their hardware. For more information about multipath, see the Configuring device mapper multipath guide.

  3. Run the following command on all Controller and Compute nodes to prevent partition creation:

    $ sed -i "s/^defaults {/defaults {\n\tskip_kpartx yes/" /etc/multipath.conf
    Note

    Setting skip_kpartx to yes prevents kpartx on the Compute node from automatically creating partitions on the device, which prevents unnecessary device mapper entries. For more information about configuration attributes, see Modifying the DM-Multipath configuration file in the Configuring device mapper multipath guide.

  4. Start the multipath daemon on all Controller and Compute nodes:

    $ systemctl enable --now multipathd
  5. Update the heat template to enable multipath:

    parameter_defaults:
      NovaLibvirtVolumeUseMultipath:  true
      NovaComputeOptVolumes:
        - /etc/multipath.conf:/etc/multipath.conf:ro
        - /etc/multipath/:/etc/multipath/:rw
      CinderVolumeOptVolumes:
        - /etc/multipath.conf:/etc/multipath.conf:ro
        - /etc/multipath/:/etc/multipath/:rw
  6. Optional: If you are using Block Storage (cinder) as an Image service (glance) back end, you must also complete the following steps:

    1. Add the following GlanceApiOptVolumes configuration to the heat template:

      parameter_defaults:
        GlanceApiOptVolumes:
          - /etc/multipath.conf:/etc/multipath.conf:ro
          - /etc/multipath/:/etc/multipath/:rw
    2. Set the ControllerExtraConfig parameter in the following way:

      parameter_defaults:
        ControllerExtraConfig:
          glance::config::api_config:
            default_backend/cinder_use_multipath:
              value: true
      Note
      Ensure that both default_backend and the GlanceBackendID heat template default value match.
  7. For every configured back end, set use_multipath_for_image_xfer to true:

    parameter_defaults:
      ExtraConfig:
        cinder::config::cinder_config:
          <backend>/use_multipath_for_image_xfer:
            value: true
  8. Run the following command to update the overcloud:

    $ openstack overcloud deploy
    Note

    When you run the openstack overcloud deploy command to install and configure multipath, you must pass all previous roles and environment files that you used to deploy the overcloud, such as --templates, --roles-file, -e for all environment files, and --timeout. Failure to pass all previous roles and environment files can cause problems with your overcloud deployment. For more information about using overcloud parameters, see Creating the Overcloud with the CLI Tools in the Director Installation and Usage guide.

2.5.3. Verifying multipath configuration

This procedure describes how to verify multipath configuration on new or existing overcloud deployments.

Procedure

  1. Create a VM.
  2. Attach a non-encrypted volume to the VM.
  3. Get the name of the Compute node that contains the instance:

    $ nova show INSTANCE | grep OS-EXT-SRV-ATTR:host

    Replace INSTANCE with the name of the VM that you booted.

  4. Retrieve the virsh name of the instance:

    $ nova show INSTANCE | grep instance_name

    Replace INSTANCE with the name of the VM that you booted.

  5. Get the IP address of the Compute node:

    $ . stackrc
    $ nova list | grep compute_name

    Replace compute_name with the name from the output of the nova show INSTANCE command.

  6. SSH into the Compute node that runs the VM:

    $ ssh heat-admin@COMPUTE_NODE_IP

    Replace COMPUTE_NODE_IP with the IP address of the Compute node.

  7. Log in to the container that runs virsh:

    $ podman exec -it nova_libvirt /bin/bash
  8. Enter the following command on a Compute node instance to verify that it is using multipath in the cinder volume host location:

    virsh domblklist VIRSH_INSTANCE_NAME | grep /dev/dm

    Replace VIRSH_INSTANCE_NAME with the output of the nova show INSTANCE | grep instance_name command.

    If the instance shows a value other than /dev/dm-, the connection is non-multipath and you must refresh the connection info with the nova shelve and nova unshelve commands:

    $ nova shelve <instance>
    $ nova unshelve <instance>
    Note

    If you have more than one type of back end, you must verify the instances and volumes on all back ends, because connection info that each back end returns might vary.