Consistency groups¶
Consistency groups enable you to create snapshots at the exact same point in time from multiple file system shares. For example, a database might place its tables, logs, and configuration on separate shares. To restore this database from a previous point in time, it makes sense to restore the logs, tables, and configuration together from the exact same point in time.
Shared File system allows you to create a snapshot of the consistency group and restore all shares that were associated with the consistency group by creating a consistency group from a snapshot.
Note
The consistency groups and snapshots are realized as an experimental Shared File Systems API. Contributors can change or remove the experimental part of the Shared File Systems API without maintaining backward compatibility. The experimental API has "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 reports. The consistency_group_support can have such values:
- pool or host. Consistency groups are supported. Specifies the level of consistency groups support.
- false. Consistency groups are not supported.
Create a new consistency group, specify a share network and one or more share types. In the example a consistency group cgroup1 was created with 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 is in available status:
$ 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 you need to create a share with a --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 | {} |
+-----------------------------+--------------------------------------+
Admin can rename the consistency group or change its description using manila cg-update command, or delete it by manila cg-delete.
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 group.
Note
The consistency group can be deleted only if it has no dependent Consistency group snapshots.
$ 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¶
You can create snapshots of consistency groups. To create a snapshot, you specify the ID or name of the consistency group that you want to snapshot. After you create a consistency group snapshot, you can create a consistency group from it.
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. |
+----------------------+--------------------------------------+
Admin can rename the consistency group snapshot or change its description using cg-snapshot-update command, or delete it by cg-snapshot-delete.
A consistency group snapshot can have members. The consistency group snapshot members are the shares that belong to some consistency group. 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, for example, 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 it:
$ 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 list of consistency group. There are two groups now:
$ 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 was created when you created a consistency group cgroup2 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 that was 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 cg-snapshot-reset-state and force-delete a specified consistency group snapshot in any state using cg-snapshot-delete with --force key. Use the policy.json file to grant permissions for these actions to other roles.
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