1.2.11 Snapshots

An Exascale snapshot is a thinly-provisioned read-only point-in-time copy of a file. The source file for a snapshot can be a regular file, a clone, or another snapshot. Exascale uses redirect-on-write techniques to create and maintain snapshots very quickly and space-efficiently.

The snapshot creation process can work on an individual file or a groups of files. All snapshots created in the same operation are point-in-time consistent, and all files in a snapshot operation must be in the same vault.

A snapshot inherits the ACL and file storage attribute settings from the original file. After creation, you can modify the snapshot ACL and any modifiable attributes independently from the original file. You can also modify, or even delete, the original file without affecting the snapshot.

You can use the ESCLI snapshotfile command to create snapshots, and you can use lssnapshots to view the association between snapshots and their sources.

While an Exascale snapshot is read-only, you can effectively manufacture a writable snapshot by creating a snapshot and then making a clone of the snapshot. In this case, the snapshot provides a durable point-in-time copy of the file, and the clone enables writing to a thinly-provisioned copy of the snapshot. At any point, you can effectively roll back to the snapshot creation time by removing and re-creating the clone.