Snapshots are a block image in the form of a storage volume or LUN used to instantaneously capture the state of a volume at a specific point in time. PowerFlex snapshots are thin-provisioned and writable. Once a snapshot is taken, it becomes a new unmapped volume in the system. It can be manipulated like any other volume exposed by the storage system: mapped, unmapped, renamed, resized, and so on.

PowerFlex snapshots can be initiated manually through any of the clients including a Web UI, CLI, or REST API. This includes the ability to create snapshot policies, which automate the creation and deletion of snapshots according to a predefined schedule of your own choosing.

Snapshots and their source volume are organized into a Volume Tree, or V-Tree. Stated differently, a V-Tree includes the root volume and all the descendant snapshots resulting from that volume. A Volume Tree includes not only snapshots taken of the root volume at different points in time, but also descendants that are snapshots of snapshots. The following diagram depicts a small V-Tree with both types of descendants.

Figure 2.   V-Tree where S111 and S112 are snapshots of volume V1 at different times, and S121 is a snapshot of another snapshot (S111)