openstack-manuals/doc/admin-guide/source/shared-file-systems-cgroups.rst

Consistency groups

Consistency groups enable you to create snapshots from multiple file system shares at the same point in time. For example, a database might place its tables, logs, and configurations on separate shares. Store logs, tables, and configurations at the same point in time to effectively restore a database.

The Shared File System service allows you to create a snapshot of the consistency group and restore all shares that were associated with a consistency group.

Important

The consistency groups and snapshots are an experimental Shared File Systems API in the Liberty release. Contributors can change or remove the experimental part of the Shared File Systems API in further releases without maintaining backward compatibility. Experimental APIs have an X-OpenStack-Manila-API-Experimental: true header in their HTTP requests.

Consistency groups

Note

Before using consistency groups, make sure the Shared File System driver that you are running has consistency group support. You can check it in the manila-scheduler service reports. The consistency_group_support can have the following values:

• pool or host. Consistency groups are supported. Specifies the level of consistency groups support.
• false. Consistency groups are not supported.

The manila cg-create command creates a new consistency group. With this command, you can specify a share network, and one or more share types. In the example a consistency group cgroup1 was created by specifying two comma-separated share types:

$ manila cg-create --name cgroup1 --description "My first CG." --share-types my_type1,default --share-network my_share_net
+----------------------+--------------------------------------+
| Property             | Value                                |
+----------------------+--------------------------------------+
| status               | creating                             |
| description          | My first CG.                         |
| source_cgsnapshot_id | None                                 |
| created_at           | 2015-09-29T15:01:12.102472           |
| share_network_id     | 5c3cbabb-f4da-465f-bc7f-fadbe047b85a |
| share_server_id      | None                                 |
| host                 | None                                 |
| project_id           | 20787a7ba11946adad976463b57d8a2f     |
| share_types          | a4218aa5-f16a-42b3-945d-113496d40558 |
|                      | c0086582-30a6-4060-b096-a42ec9d66b86 |
| id                   | 6fdd91bc-7a48-48b4-8e40-0f4f98d0ecd6 |
| name                 | cgroup1                              |
+----------------------+--------------------------------------+

Check that consistency group status is available:

$ manila cg-show cgroup1
+----------------------+--------------------------------------+
| Property             | Value                                |
+----------------------+--------------------------------------+
| status               | available                            |
| description          | My first CG.                         |
| source_cgsnapshot_id | None                                 |
| created_at           | 2015-09-29T15:05:40.000000           |
| share_network_id     | 5c3cbabb-f4da-465f-bc7f-fadbe047b85a |
| share_server_id      | None                                 |
| host                 | manila@generic1#GENERIC1             |
| project_id           | 20787a7ba11946adad976463b57d8a2f     |
| share_types          | c0086582-30a6-4060-b096-a42ec9d66b86 |
|                      | a4218aa5-f16a-42b3-945d-113496d40558 |
| id                   | 6fdd91bc-7a48-48b4-8e40-0f4f98d0ecd6 |
| name                 | cgroup1                              |
+----------------------+--------------------------------------+

To add a share to the consistency group, create a share by adding the --consistency-group option where you specify the ID of the consistency group in available status:

$ manila create nfs 1 --name "Share2" --description "My second share" \
--share-type default --share-network my_share_net --consistency-group cgroup1
+-----------------------------+--------------------------------------+
| Property                    | Value                                |
+-----------------------------+--------------------------------------+
| status                      | None                                 |
| share_type_name             | default                              |
| description                 | My second share                      |
| availability_zone           | None                                 |
| share_network_id            | None                                 |
| export_locations            | []                                   |
| share_server_id             | None                                 |
| host                        | None                                 |
| snapshot_id                 | None                                 |
| is_public                   | False                                |
| task_state                  | None                                 |
| snapshot_support            | True                                 |
| id                          | 7bcd888b-681b-4836-ac9c-c3add4e62537 |
| size                        | 1                                    |
| name                        | Share2                               |
| share_type                  | c0086582-30a6-4060-b096-a42ec9d66b86 |
| created_at                  | 2015-09-29T15:09:24.156387           |
| export_location             | None                                 |
| share_proto                 | NFS                                  |
| consistency_group_id        | 6fdd91bc-7a48-48b4-8e40-0f4f98d0ecd6 |
| source_cgsnapshot_member_id | None                                 |
| project_id                  | 20787a7ba11946adad976463b57d8a2f     |
| metadata                    | {}                                   |
+-----------------------------+--------------------------------------+

Administrators can rename the consistency group, or change its description using the manila cg-update command. Delete the group with the manila cg-delete command.

As an administrator, you can also reset the state of a consistency group and force delete a specified consistency group in any state. Use the policy.json file to grant permissions for these actions to other roles.

Use manila cg-reset-state [--state <state>] <consistency_group> to update the state of a consistency group explicitly. A valid value of a status are available, error, creating, deleting, error_deleting. If no state is provided, available will be used.

$ manila cg-reset-state cgroup1 --state error

Use manila cg-delete <consistency_group> [<consistency_group> ...] to soft-delete one or more consistency groups.

Note

A consistency group can be deleted only if it has no dependent shared-file-systems-cgsnapshots.

$ manila cg-delete cgroup1

Use manila cg-delete --force <consistency_group> [<consistency_group> ...] to force-delete a specified consistency group in any state.

$ manila cg-delete --force cgroup1

Consistency group snapshots

To create a snapshot, specify the ID or name of the consistency group. After creating a consistency group snapshot, it is possible to generate a new consistency group.

Create a snapshot of consistency group cgroup1:

$ manila cg-snapshot-create cgroup1 --name CG_snapshot1 --description "A snapshot of the first CG."
+----------------------+--------------------------------------+
| Property             | Value                                |
+----------------------+--------------------------------------+
| status               | creating                             |
| name                 | CG_snapshot1                         |
| created_at           | 2015-09-29T15:26:16.839704           |
| consistency_group_id | 6fdd91bc-7a48-48b4-8e40-0f4f98d0ecd6 |
| project_id           | 20787a7ba11946adad976463b57d8a2f     |
| id                   | 876ad24c-1efd-4607-a2b1-6a2c90034fa5 |
| description          | A snapshot of the first CG.          |
+----------------------+--------------------------------------+

Check the status of created consistency group snapshot:

$ manila cg-snapshot-show CG_snapshot1
+----------------------+--------------------------------------+
| Property             | Value                                |
+----------------------+--------------------------------------+
| status               | available                            |
| name                 | CG_snapshot1                         |
| created_at           | 2015-09-29T15:26:22.000000           |
| consistency_group_id | 6fdd91bc-7a48-48b4-8e40-0f4f98d0ecd6 |
| project_id           | 20787a7ba11946adad976463b57d8a2f     |
| id                   | 876ad24c-1efd-4607-a2b1-6a2c90034fa5 |
| description          | A snapshot of the first CG.          |
+----------------------+--------------------------------------+

Administrators can rename a consistency group snapshot, change its description using the cg-snapshot-update command, or delete it with the cg-snapshot-delete command.

A consistency group snapshot can have members. To add a member, include the --consistency-group optional parameter in the create share command. This ID must match the ID of the consistency group from which the consistency group snapshot was created. Then, while restoring data, and operating with consistency group snapshots, you can quickly find which shares belong to a specified consistency group.

You created the share Share2 in cgroup1 consistency group. Since you made a snapshot of it, you can see that the only member of the consistency group snapshot is Share2 share:

$ manila cg-snapshot-members CG_snapshot1
+--------------+------+----------------------------+----------------+--------------+--------------+
| Id           | Size | Created_at                 | Share_protocol | Share_id     | Share_type_id|
+--------------+------+----------------------------+----------------+--------------+--------------+
| 5c62af2b-... | 1    | 2015-09-29T15:26:22.000000 | NFS            | 7bcd888b-... | c0086582-... |
+--------------+------+----------------------------+----------------+--------------+--------------+

After you create a consistency group snapshot, you can create a consistency group from the new snapshot:

$ manila cg-create --source-cgsnapshot-id 876ad24c-1efd-4607-a2b1-6a2c90034fa5 --name cgroup2 --description "A consistency group from a CG snapshot."
+----------------------+-----------------------------------------+
| Property             | Value                                   |
+----------------------+-----------------------------------------+
| status               | creating                                |
| description          | A consistency group from a CG snapshot. |
| source_cgsnapshot_id | 876ad24c-1efd-4607-a2b1-6a2c90034fa5    |
| created_at           | 2015-09-29T15:47:47.937991              |
| share_network_id     | None                                    |
| share_server_id      | None                                    |
| host                 | manila@generic1#GENERIC1                |
| project_id           | 20787a7ba11946adad976463b57d8a2f        |
| share_types          | c0086582-30a6-4060-b096-a42ec9d66b86    |
|                      | a4218aa5-f16a-42b3-945d-113496d40558    |
| id                   | ffee08d9-c86c-45e5-861e-175c731daca2    |
| name                 | cgroup2                                 |
+----------------------+-----------------------------------------+

Check the consistency group list. Two groups now appear:

$ manila cg-list
+-------------------+---------+-----------------------------------------+-----------+
| id                | name    | description                             | status    |
+-------------------+---------+-----------------------------------------+-----------+
| 6fdd91bc-7a48-... | cgroup1 | My first CG.                            | available |
| ffee08d9-c86c-... | cgroup2 | A consistency group from a CG snapshot. | available |
+-------------------+---------+-----------------------------------------+-----------+

Check a list of the shares. New share with ba52454e-2ea3-47fa-a683-3176a01295e6 ID appeared after the consistency group cgroup2 was built from a snapshot with a member.

$ manila list
+------+-------+-----+------------+----------+----------+-----------+--------------------------+
| ID   | Name  | Size| Share Proto| Status   | Is Public| Share Type| Host                     |
+------+-------+-----+------------+----------+----------+-----------+--------------------------+
| 7bc..| Share2| 1   | NFS        | available| False    | c008658...| manila@generic1#GENERIC1 |
| ba5..| None  | 1   | NFS        | available| False    | c008658...| manila@generic1#GENERIC1 |
+------+-------+-----+------------+----------+----------+-----------+--------------------------+

Print detailed information about new share:

Note

Pay attention on the source_cgsnapshot_member_id and consistency_group_id fields in a new share. It has source_cgsnapshot_member_id that is equal to the ID of the consistency group snapshot and consistency_group_id that is equal to the ID of cgroup2 created from a snapshot.

$ manila show ba52454e-2ea3-47fa-a683-3176a01295e6
+-----------------------------+---------------------------------------------------------------+
| Property                    | Value                                                         |
+-----------------------------+---------------------------------------------------------------+
| status                      | available                                                     |
| share_type_name             | default                                                       |
| description                 | None                                                          |
| availability_zone           | None                                                          |
| share_network_id            | None                                                          |
| export_locations            | 10.254.0.5:/shares/share-5acadf4d-f81a-4515-b5ce-3ab641ab4d1e |
| share_server_id             | None                                                          |
| host                        | manila@generic1#GENERIC1                                      |
| snapshot_id                 | None                                                          |
| is_public                   | False                                                         |
| task_state                  | None                                                          |
| snapshot_support            | True                                                          |
| id                          | ba52454e-2ea3-47fa-a683-3176a01295e6                          |
| size                        | 1                                                             |
| name                        | None                                                          |
| share_type                  | c0086582-30a6-4060-b096-a42ec9d66b86                          |
| created_at                  | 2015-09-29T15:47:48.000000                                    |
| share_proto                 | NFS                                                           |
| consistency_group_id        | ffee08d9-c86c-45e5-861e-175c731daca2                          |
| source_cgsnapshot_member_id | 5c62af2b-0870-4d00-b3fa-174831eb15ca                          |
| project_id                  | 20787a7ba11946adad976463b57d8a2f                              |
| metadata                    | {}                                                            |
+-----------------------------+---------------------------------------------------------------+

As an administrator, you can also reset the state of a consistency group snapshot with the cg-snapshot-reset-state command, and force delete a specified consistency group snapshot in any state using the cg-snapshot-delete command with the --force key. Use the policy.json file to grant permissions for these actions to other roles.