Red Hat OpenStack Administration I: Core Operations for Domain Operators

Cloud users create volumes to attach them to a running instance to give them persistent storage. They can attach and detach the volume at will; the volume can be attached to another instance at any time. To create a volume using the CLI, use the openstack volume create command.

The following example demonstrates the use of the openstack volume create command.

[user@demo ~(admin)]$ openstack volume create \
> --size 10 \
> demo-volume1
+---------------------+--------------------------------------+
| Field               | Value                                |
+---------------------+--------------------------------------+
| attachments         | []                                   |
| availability_zone   | nova                                 |
| bootable            | false                                |
| consistencygroup_id | None                                 |
| created_at          | 2020-06-10T21:22:17.000000           |
| description         | None                                 |
| encrypted           | False                                |
| id                  | e8efc7b8-4dfe-4667-be8a-4ac58c1fd8a9 |
| migration_status    | None                                 |
| multiattach         | False                                |
| name                | demo-volume1                         |
| properties          |                                      |
| replication_status  | None                                 |
| size                | 10                                   |
| snapshot_id         | None                                 |
| source_volid        | None                                 |
| status              | creating                             |
| type                | tripleo                              |
| updated_at          | None                                 |
| user_id             | 40da11b61dae43248a0b8f7e42a14128     |
+---------------------+--------------------------------------+

A volume can be attached to a running instance. Use the openstack server add volume command to attach a volume to an instance. Users can log in to the instance and mount, format, and use the disk after attaching the volume.

[user@demo ~(admin)]$ openstack server add volume \
> demo-server1 demo-volume1

A volume can also be detached from an instance with the openstack server remove volume command.

[user@demo ~(admin)]$ openstack server remove volume \
> demo-server1 demo-volume1

The status of the volume can be viewed with the openstack volume list command. The volume status can be either Available or In-Use. Use the openstack volume list command to view the volumes.

[user@demo ~(admin)]$ openstack volume list -f json
[
  {
    "ID": "e8efc7b8-4dfe-4667-be8a-4ac58c1fd8a9",
    "Name": "demo-volume1",
    "Status": "available",
    "Size": 10,
    "Attached to": []
  }
]

Use the openstack volume delete command to remove a volume. Separate the volume name or ID with a space to delete more than one volume.

[user@demo ~(admin)]$ openstack volume delete demo-volume1

Some use cases require a volume to be shared between users in different projects. To transfer a volume, the volume must be in the available state. This means that the volume must not be attached to any instance at the time the transfer is performed.

When the transfer is performed, either using the CLI or the Dashboard, the user transferring the volume gets both a transfer ID and an authorization key. The transfer ID and the authorization key must be provided to the user receiving the volume transfer in order for the user to be able to accept the transfer. Until the transfer is accepted by the user receiving the volume transfer, the volume is only available to the user creating the transfer. When the transfer is accepted, the volume is no longer available to the user creating the transfer, and it becomes available to the user accepting the volume transfer.

As a domain operator you need to understand the following steps to advise your cloud users how to perform a volume transfer.

Volume backups differ from volume snapshots. Backups are usually stored in a different location and preserve the data in the object storage back end. Snapshots use the same location as volumes and maintain the state of a volume at a certain point in time. Snapshots are also used to clone and create a new volume.

Use the openstack volume snapshot create command to create a snapshot. Use the --force option if the volume is attached to an instance.

[user@demo ~(admin)]$ openstack volume snapshot create \
> --volume demo-volume1 MySnapshot
+-------------+--------------------------------------+
| Field       | Value                                |
+-------------+--------------------------------------+
| created_at  | 2020-06-10T23:49:36.457518           |
| description | None                                 |
| id          | 697d6394-2ce0-49e8-8180-2624a2303b60 |
| name        | MySnapshot                           |
| properties  |                                      |
| size        | 10                                   |
| status      | creating                             |
| updated_at  | None                                 |
| volume_id   | e8efc7b8-4dfe-4667-be8a-4ac58c1fd8a9 |
+-------------+--------------------------------------+

Use the openstack volume snapshot list command to view a list of snapshots.

[user@demo ~(admin)]$ openstack volume snapshot list
[
  {
    "ID": "697d6394-2ce0-49e8-8180-2624a2303b60",
    "Name": "MySnapshot",
    "Description": null,
    "Status": "available",
    "Size": 10
  }
]

Use the openstack volume snapshot delete command to delete snapshots. To delete more than one snapshot, separate the names with spaces.

[user@demo ~(admin)]$ openstack volume snapshot delete MySnapshot

The Block Storage backup service is used to perform full or incremental backups, and to restore a backup to a volume. The volume backup server component maintains the volume backups, which can be used to construct an identical volume. The OpenStack Block Storage service's backup component uses the OpenStack object store as the storage back end to accommodate the archives of the persistent volumes that act as volume backups. This component can also be configured to use Red Hat Ceph Storage as the back-end storage provider. You can use the openstack volume backup create command to create backups, and use the --incremental option to create incremental volume backups.

The domain operator can create different volume types. The volume types help offer different storage back ends and an abstract collection of criteria to characterize volumes, such as gold and silver volume types, as a tiered level of storage. Volume types can be encrypted to add security, and also associated with Quality of Service (QoS) to add features to the storage. RHOSP ships with two volume types: the tripleo volume type is the default storage and points to a Ceph back end; and Red Hat OpenStack Platform Director installs it. The __DEFAULT__ volume type is hard-coded in the product, and it is used when the default_volume_type option is not set in cinder.conf.

Use the openstack volume type create command to create volume types.

[user@demo ~(admin)]$ openstack volume type create \
> --public --encryption-provider luks vt-encrypted
+-------------+------------------------------------------------------------------+
| Field       | Value                                                            |
+-------------+------------------------------------------------------------------+
| description | None                                                             |
| encryption  | cipher=, control_location='front-end',                           |
|             | encryption_id='a5bb24a0-e434-4b45-801e-43afed5472bc', key_size=, |
|             | provider='luks'                                                  |
| id          | 0febf435-c005-4f44-97c4-6353406bc587                             |
| is_public   | True                                                             |
| name        | vt-encrypted                                                     |
+-------------+------------------------------------------------------------------+

Use the openstack volume qos associate command to associate Quality of Service to a volume type.

[user@demo ~(admin)]$ openstack volume qos associate \
> qos-limit-iops vt-encrypted