You can make a backup of a block volume accessible to hosts by mapping the host to a snapshot of the volume. This can be any snapshot on the volume path or on a path that includes the volume path. It can be a snapshot taken manually or from a local protected path.
When you assign hosts to a snapshot of a volume, VMS generates a globally unique UUID and namespace ID that is unique within the subsystem and assigns it to the mapping, enabling the assigned hosts to access the snapshot as a read-only volume. (These identifiers are destroyed if all hosts are unmapped from the snapshot.)
Snapshots that are mapped to hosts cannot be deleted.
If a volume is deleted, but you have the volume backed up by a snapshot, you can make the data available by mapping the volume to host from the snapshot. You need to know the name of the volume that was deleted.
Assigning Hosts to Volume Snapshots from the VAST Web UI
In the Volumes tab, right-click the volume and select Manage Mappings.
Select the hosts that you want to map to the snapshot.
Click Available volume snapshots.
All available snapshots of the volume are shown. You can see the ID, Name, Path and Creation Time of each snapshot.
Select the snapshot from which you want to map the volume to the selected host(s).
Click Save And Go To Mapping.
Click Save Mapping.
The mapping task begins and you can track it in the Activities page.
When the mapping is complete, you can see details of the new snapshot volume in the Volumes tab, where the Snapshot ID column identifies the snapshot.
Mapping a Volume from a Snapshot
You can also map a snapshot volume from a snapshot.
In the Data Protection page, select the Snapshots tab.
Find the snapshot that you want to use. This can be a specific snapshot of the volume path or a snapshot of the subsystem path or a snapshot of a path under the subsystem that includes the volume.
Right-click the snapshot and select Map Snapshot Volumes.
The Map Volumes dialog suggests volumes.
In the Map Volumes dialog, select the volume you want to map from the snapshot.
Note
It's possible that volumes that are not actually included in the snapshot will be suggested. Make sure the volume you want resides under the snapshot path before you proceed.
Click Next.
Select the volume path on the left and the host(s) on the right.
Click Save Mapping.
The mapping task begins and you can track it in the Activities page.
Mapping a Volume from a Snapshot after the Volume was Deleted
If the volume has been deleted but there is a snapshot of the volume and you want to enable a host to access the backup from the snapshot, you can use the following procedure. You will need to know the name of the volume and to which subsystem it belonged.
In the Data Protection page, select the Snapshots tab.
Find the snapshot that you want to use. This can be a specific snapshot of the volume path or a snapshot of the subsystem path or a snapshot of a path under the subsystem that includes the volume.
Right-click the snapshot and select Map Snapshot Volumes.
In the Map Volumes dialog, click Add volumes manually. (This appears at the top left of the table.)
From the Subsystem dropdown, select the subsystem under which the volume existed before it was deleted.
In the Volume Name field, enter the volume name.
Click Add to table.
Select the new row that was added to the table.
Click Next.
Select the volume path on the left and the host(s) on the right.
Click Save Mapping.
The mapping task begins and you can track it in the Activities page.
Assigning Hosts to Snapshot Volumes in VAST CLI
To list block hosts: blockhost list. For example:
vcli: admin> blockhost list
+----+-----------+------------+----------------------------------------------------------------------+------+-------------+
| Id | Tenant-id | Name | Nqn | Tags | Tenant-name |
+----+-----------+------------+----------------------------------------------------------------------+------+-------------+
| 2 | 1 | blockhost1 | nqn.2014-08.org.nvmexpress:uuid:4c4c4544-004e-3310-804d-c6c04f4b3234 | {} | default |
+----+-----------+------------+----------------------------------------------------------------------+------+-------------+To list volumes: volume list. For example:
vcli: admin> volume list
+----+---------+--------------+----------+-------------------------------------+--------------+--------------------------------------+--------------------------------------+--------------+-------------+-------------+
| Id | View-id | Name | Size(GB) | Tags | Namespace-id | Nguid | Uuid | Capacity(GB) | Snapshot-id | Tenant-name |
+----+---------+--------------+----------+-------------------------------------+--------------+--------------------------------------+--------------------------------------+--------------+-------------+-------------+
| 3 | 3 | dev/mgmt | 1.000 | {} | None | f88cd191-8c87-2686-806e-6538ae910f9f | f88cd191-14f7-4c86-806e-6538ae910f9f | 0.000 | N/A | default |
| 1 | 3 | dev/platform | 1.000 | {'team': 'platform', 'owner': 'DG'} | 1 | b1ee2839-8c87-26ab-982d-e4bf5541273b | b1ee2839-0fc4-4dab-982d-e4bf5541273b | 0.000 | N/A | default |
+----+---------+--------------+----------+-------------------------------------+--------------+--------------------------------------+--------------------------------------+--------------+-------------+-------------+To list available snapshots of a volume: volume get_snapshots. For example, referencing the volume ID from the volume list output:
vcli: admin> volume get_snapshots --id 1 +----+---------+------+----------+------+--------------+-------+------+--------------+-------------+-------------+ | Id | View-id | Name | Size(GB) | Tags | Namespace-id | Nguid | Uuid | Capacity(GB) | Snapshot-id | Tenant-name | +----+---------+------+----------+------+--------------+-------+------+--------------+-------------+-------------+ | 1 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | | 2 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | | 3 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | | 4 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | | 5 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | | 6 | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | +----+---------+------+----------+------+--------------+-------+------+--------------+-------------+-------------+
To assign hosts to a snapshot of a volume, use blockmapping map_volume_path. You will need the full volume path, formed by concatenating the view path and the volume name. For example:
vcli: admin> view show --id 3
+---------------------------------+---------------------------------------------------------------------------------------------------+
| ID | 3 |
| Path | /myblocksystem
...
vcli: admin> volume list
+----+---------+--------------+----------+-------------------------------------+--------------+--------------------------------------+--------------------------------------+--------------+-------------+-------------+
| Id | View-id | Name | Size(GB) | Tags | Namespace-id | Nguid | Uuid | Capacity(GB) | Snapshot-id | Tenant-name |
+----+---------+--------------+----------+-------------------------------------+--------------+--------------------------------------+--------------------------------------+--------------+-------------+-------------+
| 3 | 3 | my/volume | 1.000 | {} | None | f88cd191-8c87-2686-806e-6538ae910f9f | f88cd191-14f7-4c86-806e-6538ae910f9f | 0.000 | N/A | default |
| 1 | 3 | dev/platform | 1.000 | {'team': 'platform', 'owner': 'DG'} | 1 | b1ee2839-8c87-26ab-982d-e4bf5541273b | b1ee2839-0fc4-4dab-982d-e4bf5541273b | 0.000 | N/A | default |
+----+---------+--------------+----------+-------------------------------------+--------------+--------------------------------------+--------------------------------------+--------------+-------------+-------------+
vcli: admin> blockmapping map_volume_path --volume-full-path /myblocksubsystem/my/volume --snapshot-id 6 --blockhost-ids 2,3,4