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Mainframe Enablers TimeFinder SnapVX and zDP 8.5 Product Guide

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Introduction to TimeFinder SnapVX

Starting with HYPERMAX OS 5977, TimeFinder introduces TimeFinder SnapVX which provides the best aspects of the traditional TimeFinder offerings, together with increased scalability and ease-of-use.

SnapVX provides targetless snapshot capabilities. Instead of requiring target volumes to capture point-in-time images of source volumes, SnapVX introduces the new concept of creating a “snapshot” to create and access point-in-time images of volumes. SnapVX supports up to 256 snapshots per volume which effectively allows for the creation of 256 separate point-in-time images of every volume. Snapshots store changed tracks (deltas) directly in the Storage Resource Pool of the source device and use shared allocations to eliminate saving duplicate tracks between multiple snapshots. Users can assign names to individual snapshots and assign an automatic expiration date to each snapshot.

NOTE:The PowerMax Family Product Guide and VMAX All Flash Product Guide provide additional information about SnapVX.

Linking snapshots to targets

With SnapVX, a snapshot can be accessed by linking it to a host accessible volume (known as a target volume). Up to 1024 target volumes can be linked to one or more snapshots of a single source volume. The 1024 links can all be to the same snapshot on a single source volume, or they can be multiple target volumes that are linked to multiple snapshots from the same source volume.

NOTE:A target volume may be linked only to one snapshot at a time.

You can link, unlink, relink snapshots to the same set of target volumes, providing flexibility in the point-in-time copy that is presented on a single set of target devices. These snapshots share allocations to the same track image whenever possible while ensuring they each continue to represent a unique point-in-time image of the source volume. Despite the space efficiency that is achieved through shared allocation to unchanged data, additional capacity is required to preserve the preupdate images of changed tracks that each point-in-time snapshot captures.

Cascading snapshots

Snapshots can be cascaded from linked targets, and targets can be linked to snapshots of linked targets. There is no limit to the number of levels of cascading, and the cascade can be broken.

COPY and NOCOPY mode

Targets can be linked in COPY mode to create full-copy clones. If an application is to find a particular point-in-time copy among a large set of snapshots, SnapVX enables you to link and relink until the correct snapshot is located.

If the linked target is in NOCOPY mode, a cascading snapshot is a dependent snapshot. A target device cannot be unlinked without removing dependent snapshots. Or, the snapshots should be removed in the reverse order of creation.

NOTE:For information about how target volume tracks are defined, see Target volume track definition.

Starting with PowerMaxOS 5978.669.669, you can use NOCOPY mode for SnapVX target devices that are R1s.

Backward compatibility to traditional TimeFinder products

TimeFinder SnapVX supports backward compatibility to traditional TimeFinder products, including TimeFinder/Clone, TimeFinder VP Snap, and TimeFinder/Mirror.

TimeFinder transparently converts the commands of the traditional TimeFinder products to SnapVX commands.

NOTE:Using TimeFinder SnapVX requires no change of scripts that use the traditional TimeFinder commands.

TimeFinder emulation sessions and TimeFinder snapshots can coexist on the same device.

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