Mainframe Enablers TimeFinder SnapVX and zDP 8.5 Product Guide

After a LINK operation has completed, a background task is started to “define” each track on the target volume. The definition process changes each track in the target volume to indicate the corresponding track of its linked snapshot.

Once a track has been defined, it remains to indicate to this new track even after the unlink process. The result is that a fully defined target device (linked or unlinked) looks like the source device at the time the snapshot was created.

This definition process is not a physical copy operation, but rather a manipulation of in memory track pointers. If the link operation was done in MODE(NOCOPY), the target and snapshot share physical tracks until a write is performed on the target device. If the snapshot was linked in MODE(COPY), a subsequent background copy process copies the snapshot data and assigns these new unshared tracks to the target.

You can determine whether SnapVX waits for all target tracks to be defined before unlinking the target device. For this purpose, use the WAIT_FOR_Definition parameter on the UNLINK (or TERMINATE) command.