Snapshots are supported from VAST Cluster 2.0.0.
A snapshot is a reference point that preserves the exact folder structure and data content of a data path at a point in time. Snapshots serve as a virtual copy of the data you had at previous points in time and enable you to restore files or directories after deletion or modification.
You can take a snapshot of any directory at any time and you can create snapshot policies to schedule periodic snapshots of specified directories.
Snapshots can be viewed in a hidden read-only directory called .snapshot, which is visible under the directory of which the snapshot is taken.
For example: A snapshot of the path /a/b is created. The snapshot is named MySnapshot_b. The snapshot is visible as a directory called MySnapshot_b under /a/b/.snapshot. The content of /a/b/.snapshot/MySnapshot_b is identical to the content of /a/b at the time of snapshot creation.
Snapshots consume space when they hold on to storage that would have otherwise been released. This can happen when files are deleted or existing blocks are overwritten with new data. In these cases, the snapshot holds onto the original data.
The Auxiliary used physical capacity value, which you can view on the Dashboard, closely indicates how much capacity is currently being used by snapshots. To see this value, go to the Dashboard (click and select Dashboard) and click the PHYSICAL dial:
Auxiliary used is the amount of physical SSD space in use by (a) snapshots and (b) any data that may be pending deletion at the current time. This figure usually gives a close indication of snapshot capacity usage. However, at times when a large amount of data was recently deleted, wiping that data from physical storage may taken some time and temporarily enlarge this figure.
Since snapshots only indirectly consume storage (by holding onto storage that would otherwise be released), you cannot directly control the storage consumed by snapshots. However, you can effectively limit the amount of storage consumed when you set up a snapshot policy for each data path; you choose how frequently a new snapshot is taken and how many snapshots to retain for that path.
When you take a snapshot of a nested directory, the entire file system data is preserved in the snapshot. Capacity consumption of a snapshot therefore depends on the delta of the entire file system data between the live data and the data at the time of taking the snapshot.
No. Snapshots do not consume quota.
No. When you take a snapshot of a directory, pre-existing snapshots of subdirectories are not included in the data preserved by the snapshot.
Snapshots are part of the logical realm. Managers with permission for the logical realm can manage snapshots. Managers who have object-level permission to access a specific export can also manage snapshots for that export.
You can restore files and directories via linux commands. Currently, the snapshots feature does not support reverting or cloning.
Yes, you can lock a snapshot and then it won't be deleted unless and until you unlock it.
From VAST Cluster 2.1.0, the maximum number of snapshots maintained at any time is 1000. In earlier releases, the maximum is 50. New snapshots cannot be created to exceed this maximum until and unless an old snapshot is deleted, whether manually or due to expiration or retention limit. When an old snapshot is deleted due to a retention limit in a snapshot policy, the new snapshot is created before the old snapshot is deleted.