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Taikun OCP Guide

Table of Contents

Consistency groups

Consistency group support is available in OpenStack Block Storage.
The support is added for creating snapshots of consistency groups. This
feature leverages the storage level consistency technology. It allows
snapshots of multiple volumes in the same consistency group to be taken
at the same point-in-time to ensure data consistency. The consistency
group operations can be performed using the Block Storage command
line.

Note

The Consistency Group APIs have been deprecated since the Queens
release. Use the Generic Volume Group APIs instead.

The Consistency Group APIs are governed by the same policies as the
Generic Volume Group APIs. For information about configuring cinder
policies, see policy-configuration.

Before using consistency groups, make sure the Block Storage driver
that you are running has consistency group support by reading the Block
Storage manual or consulting the driver maintainer. There are a small
number of drivers that have implemented this feature. The default LVM
driver does not support consistency groups yet because the consistency
technology is not available at the storage level.

The following consistency group operations are supported:

  • Create a consistency group, given volume types.

    Note

    A consistency group can support more than one volume type. The
    scheduler is responsible for finding a back end that can support all
    given volume types.

    A consistency group can only contain volumes hosted by the same back
    end.

    A consistency group is empty upon its creation. Volumes need to be
    created and added to it later.

  • Show a consistency group.

  • List consistency groups.

  • Create a volume and add it to a consistency group, given volume
    type and consistency group id.

  • Create a snapshot for a consistency group.

  • Show a snapshot of a consistency group.

  • List consistency group snapshots.

  • Delete a snapshot of a consistency group.

  • Delete a consistency group.

  • Modify a consistency group.

  • Create a consistency group from the snapshot of another
    consistency group.

  • Create a consistency group from a source consistency
    group.

The following operations are not allowed if a volume is in a
consistency group:

  • Volume migration.

  • Volume retype.

  • Volume deletion.

    Note

    A consistency group has to be deleted as a whole with all the
    volumes.

The following operations are not allowed if a volume snapshot is in a
consistency group snapshot:

  • Volume snapshot deletion.

    Note

    A consistency group snapshot has to be deleted as a whole with all
    the volume snapshots.

The details of consistency group operations are shown in the
following.

Note

Currently, no OpenStack client command is available to run in place
of the cinder consistency group creation commands. Use the cinder
commands detailed in the following examples.

Create a consistency group:

cinder consisgroup-create
[--name name]
[--description description]
[--availability-zone availability-zone]
volume-types

Note

The parameter volume-types is required. It can be a list
of names or UUIDs of volume types separated by commas without spaces in
between. For example,
volumetype1,volumetype2,volumetype3..

$ cinder consisgroup-create --name bronzeCG2 volume_type_1

+-------------------+--------------------------------------+
|      Property     |                Value                 |
+-------------------+--------------------------------------+
| availability_zone |                 nova                 |
|     created_at    |      2014-12-29T12:59:08.000000      |
|    description    |                 None                 |
|         id        | 1de80c27-3b2f-47a6-91a7-e867cbe36462 |
|        name       |              bronzeCG2               |
|       status      |               creating               |
+-------------------+--------------------------------------+

Show a consistency group:

$ cinder consisgroup-show 1de80c27-3b2f-47a6-91a7-e867cbe36462

+-------------------+--------------------------------------+
|      Property     |                Value                 |
+-------------------+--------------------------------------+
| availability_zone |                 nova                 |
|     created_at    |      2014-12-29T12:59:08.000000      |
|    description    |                 None                 |
|         id        | 2a6b2bda-1f43-42ce-9de8-249fa5cbae9a |
|        name       |              bronzeCG2               |
|       status      |              available               |
|     volume_types  |              volume_type_1           |
+-------------------+--------------------------------------+

List consistency groups:

$ cinder consisgroup-list

+--------------------------------------+-----------+-----------+
|                  ID                  |   Status  |    Name   |
+--------------------------------------+-----------+-----------+
| 1de80c27-3b2f-47a6-91a7-e867cbe36462 | available | bronzeCG2 |
| 3a2b3c42-b612-479a-91eb-1ed45b7f2ad5 |   error   |  bronzeCG |
+--------------------------------------+-----------+-----------+

Create a volume and add it to a consistency
group
:

Note

When creating a volume and adding it to a consistency group, a volume
type and a consistency group id must be provided. This is because a
consistency group can support more than one volume type.

$ openstack volume create --type volume_type_1 --consistency-group \
  1de80c27-3b2f-47a6-91a7-e867cbe36462 --size 1 cgBronzeVol

+---------------------------------------+--------------------------------------+
| Field                                 | Value                                |
+---------------------------------------+--------------------------------------+
|              attachments              |                  []                  |
|           availability_zone           |                 nova                 |
|                bootable               |                false                 |
|          consistencygroup_id          | 1de80c27-3b2f-47a6-91a7-e867cbe36462 |
|               created_at              |      2014-12-29T13:16:47.000000      |
|              description              |                 None                 |
|               encrypted               |                False                 |
|                   id                  | 5e6d1386-4592-489f-a56b-9394a81145fe |
|                metadata               |                  {}                  |
|                  name                 |             cgBronzeVol              |
|         os-vol-host-attr:host         |      server-1@backend-1#pool-1       |
|     os-vol-mig-status-attr:migstat    |                 None                 |
|     os-vol-mig-status-attr:name_id    |                 None                 |
|      os-vol-tenant-attr:tenant_id     |   1349b21da2a046d8aa5379f0ed447bed   |
|   os-volume-replication:driver_data   |                 None                 |
| os-volume-replication:extended_status |                 None                 |
|           replication_status          |               disabled               |
|                  size                 |                  1                   |
|              snapshot_id              |                 None                 |
|              source_volid             |                 None                 |
|                 status                |               creating               |
|                user_id                |   93bdea12d3e04c4b86f9a9f172359859   |
|              volume_type              |            volume_type_1             |
+---------------------------------------+--------------------------------------+

Create a snapshot for a consistency group:

$ cinder cgsnapshot-create 1de80c27-3b2f-47a6-91a7-e867cbe36462

+---------------------+--------------------------------------+
|       Property      |                Value                 |
+---------------------+--------------------------------------+
| consistencygroup_id | 1de80c27-3b2f-47a6-91a7-e867cbe36462 |
|      created_at     |      2014-12-29T13:19:44.000000      |
|     description     |                 None                 |
|          id         | d4aff465-f50c-40b3-b088-83feb9b349e9 |
|         name        |                 None                 |
|        status       |               creating               |
+---------------------+-------------------------------------+

Show a snapshot of a consistency group:

$ cinder cgsnapshot-show d4aff465-f50c-40b3-b088-83feb9b349e9

List consistency group snapshots:

$ cinder cgsnapshot-list

+--------------------------------------+--------+----------+
|                  ID                  | Status | Name     |
+--------------------------------------+--------+----------+
| 6d9dfb7d-079a-471e-b75a-6e9185ba0c38 | available  | None |
| aa129f4d-d37c-4b97-9e2d-7efffda29de0 | available  | None |
| bb5b5d82-f380-4a32-b469-3ba2e299712c | available  | None |
| d4aff465-f50c-40b3-b088-83feb9b349e9 | available  | None |
+--------------------------------------+--------+----------+

Delete a snapshot of a consistency group:

$ cinder cgsnapshot-delete d4aff465-f50c-40b3-b088-83feb9b349e9

Delete a consistency group:

Note

The force flag is needed when there are volumes in the consistency
group:

$ cinder consisgroup-delete --force 1de80c27-3b2f-47a6-91a7-e867cbe36462

Modify a consistency group:

cinder consisgroup-update
[--name NAME]
[--description DESCRIPTION]
[--add-volumes UUID1,UUID2,......]
[--remove-volumes UUID3,UUID4,......]
CG

The parameter CG is required. It can be a name or UUID
of a consistency group. UUID1,UUID2,…… are UUIDs of one or more
volumes to be added to the consistency group, separated by commas.
Default is None. UUID3,UUID4,…… are UUIDs of one or more volumes to
be removed from the consistency group, separated by commas. Default is
None.

$ cinder consisgroup-update --name 'new name' \
  --description 'new description' \
  --add-volumes 0b3923f5-95a4-4596-a536-914c2c84e2db,1c02528b-3781-4e32-929c-618d81f52cf3 \
  --remove-volumes 8c0f6ae4-efb1-458f-a8fc-9da2afcc5fb1,a245423f-bb99-4f94-8c8c-02806f9246d8 \
  1de80c27-3b2f-47a6-91a7-e867cbe36462

Create a consistency group from the snapshot of another
consistency group
:

$ cinder consisgroup-create-from-src
[--cgsnapshot CGSNAPSHOT]
[--name NAME]
[--description DESCRIPTION]

The parameter CGSNAPSHOT is a name or UUID of a snapshot
of a consistency group:

$ cinder consisgroup-create-from-src \
  --cgsnapshot 6d9dfb7d-079a-471e-b75a-6e9185ba0c38 \
  --name 'new cg' --description 'new cg from cgsnapshot'

Create a consistency group from a source consistency
group
:

$ cinder consisgroup-create-from-src
[--source-cg SOURCECG]
[--name NAME]
[--description DESCRIPTION]

The parameter SOURCECG is a name or UUID of a source
consistency group:

$ cinder consisgroup-create-from-src \
  --source-cg 6d9dfb7d-079a-471e-b75a-6e9185ba0c38 \
  --name 'new cg' --description 'new cloned cg'

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