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 PowerFlex Manager 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)