Home > Storage > PowerMax and VMAX > Mainframe > Dell PowerMax: Data Protector for z Systems (zDP) Essentials > TimeFinder SnapVX explained
TimeFinder SnapVX is a Dell Technologies software product that provides space-efficient, volume snap capabilities on the PowerMax storage platform. Built on thin (virtual) provisioning, TimeFinder/SnapVX supports up to 256 ‘target-less’ snapshots on each source volume. The target-less ability provides a reduction in both metadata footprint and capacity consumption while allowing many snaps to be created with minimal impact to application performance. Customers can link one snapshot to multiple target volumes to have multiple copies of data and data versioning when needed. However, customers do not need to link a snapshot to a target volume until users need to use the data from the snapshot in a meaningful way. Because snapshots are a Read-Only structure, the changes made on the source volume will not propagate to the snapshot.
A snapshot can be viewed as a container that saves the pointers of the source volume. When a snapshot is no longer needed, customers can unlink the target volume from the snapshot and terminate the snapshot. This is a fast and efficient way to reclaim any space that a snapshot has (only unique allocations to that snapshot would eventually be freed).
Finally, it is important to differentiate between a snapshot and a snapset. A snapshot represents the pointer based, point-in-time image of one volume. This is what SnapVX primarily does. A snapset is the pointer-based image of a point in time copy of multiple volumes within a single Versioned Data Group (VDG). For example, VDG EMCVDG may have snapshots of volumes AAAAAA, BBBBBB, and CCCCCC. Snapset terminology is unique to zDP.
Three snapshots of a production volume were taken. To use the data in the third snapshot, use the LINK command.
This figure shows the relationships between source devices for snapshots and target devices for snapshots. The dotted line indicates the mutually exclusive relationship between snapshots and a single target volume. While not depicted here, it is also possible to cascade copies by taking snapshots from linked targets.