How ShadowImage works

ShadowImage User Guide

Part Number

A pair is created when you:

  • Select a volume that you want to duplicate. This becomes the primary volume (P-VOL).
  • Identify another volume to contain the copy. This becomes the secondary volume (S-VOL).
  • Associate the P-VOL and S-VOLs.
  • Perform the initial copy.

During the initial copy, the P-VOL remains available for read/write. After the copy is completed, subsequent write operations to the P-VOL are regularly duplicated to the S-VOL.

The P-VOL and S-VOLs remain paired until they are split. The P-VOL for a split pair continues to be updated but data in the S-VOL remains as it was at the time of the split. The S-VOL contains a mirror image of the original volume at that point in time.

  • S-VOL data is consistent and usable. It is available for read/write access by secondary host applications.
  • Changes to the P-VOLs and S-VOLs are managed by differential bitmaps.
  • You can pair the volumes again by resynchronizing the update data from P-VOL to S-VOL, or from S-VOL to P-VOL.
Note: In Device Manager - Storage Navigator (HDvM - SN), the source volume is called P-VOL and the destination volume is called S-VOL.