Chapter 2. Block Storage and volumes

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.

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 2.2.1.5, “Create and Configure Private Volume Types”.

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

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:

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.

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 2.2.1, “Group volume settings with volume types” and Section 2.2.1.2, “Create and Configure a Volume Type”. For instructions on how to set QoS specs, Section 2.2.4, “Use Quality-of-Service specifications”.

See Section 2.3.11, “Changing the Type of a Volume (Volume Re-typing)” for information about volume re-typing.

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

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:

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 2.2.1.2, “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 2.2.5.2, “Configure Volume Type Encryption Through the CLI”.

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

To configure Block Storage volume encryption, do the following:

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

By default, the Block Storage security policy disables consistency group APIs. You must enable it before using the feature.

To enable consistency groups, 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 using the openstack overcloud deploy command.

Add a new section to an environment file using CinderApiPolicies to set the consistency group settings. For example:

parameter_defaults:
  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' }

For increased security, make the permissions for both consistency group API and volume type management API identical. The volume type management API is set to "rule:admin_or_owner" by default.

"volume_extension:types_manage": "rule:admin_or_owner",

After creating 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 to which you added the CinderApiPolicies settings.

For additional information on the openstack overcloud deploy command, refer to Creating the Overcloud with the CLI Tools section in the Director Installation and Usage Guide.

After enabling the consistency groups API, you can then start creating consistency groups. To do so:

You can change the name or description of a consistency group by selecting Edit Consistency Group from its Action column.

In addition, you can also add or remove volumes from a consistency group directly. To do so:

After adding volumes to a consistency group, you can now create snapshots from it. Before doing so, first log in as admin user from the command line on the node hosting the openstack-cinder-api and run:

# export OS_VOLUME_API_VERSION=2

Doing so will configure the client to use version 2 of openstack-cinder-api.

To list all available consistency groups (along with their respective IDs, which you will need later):

# cinder consisgroup-list

To create snapshots using the consistency group, run:

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

Where:

To display a list of all available consistency group snapshots, run:

# cinder cgsnapshot-list

Consistency groups can also be used 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.

To clone an existing consistency group:

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

Where: - 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).

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.

Create a volume transfer from the dashboard

Accept a volume transfer from the dashboard

When using Red Hat Ceph 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.

When you migrate a volume between hosts, both hosts must reside on the same back end. Use the dashboard to migrate a volume between hosts:

Migrating a volume between back ends involves volume re-typing. This means that to migrate to a new back end:

When you define the back end as an Extra Spec, use volume_backend_name as the Key. Its corresponding value is the back end’s name, as defined in the cinder.conf Block Storage configuration file. In this file, each back end is defined in its own section, and its corresponding name is set in the volume_backend_name parameter.

After you have a back end defined in a target volume type, you can migrate a volume to that back end through re-typing. This involves re-applying the target volume type to a volume, thereby applying the new back end settings. See Section 2.3.11, “Changing the Type of a Volume (Volume Re-typing)”.