The following figure shows an example of using FlashCopy® with ShadowImage for Mainframe.
Typically, you must specify an unpaired volume (with the Simplex status) as a copy source (S-VOL) or a copy target (T-VOL). When you specify an SIz P-VOL as a copy source, you can establish a FlashCopy® relationship only if the SIz pair does not have the status of Resync-R/REVRSY.
You can establish or release a FlashCopy® relationship if you meet the requirements described in Copying by volume or Copying by dataset (Compatible FlashCopy® V2_only). When there is a FlashCopy® relationship, you cannot perform backward resynchronization (Reverse Resync or Quick Restore) on the SIz pair.
Even if the SIz P-VOL already has three S-VOLs, you can create up to 16 pairs by specifying the FlashCopy® relationships with the shared S-VOL (SIz P-VOL) as the copy source.
You cannot create SIz pairs in the following cases, (see the following figure).
- The FlashCopy® S-VOL (source volume) and the SIz S-VOL (secondary volume) are shared.
- The FlashCopy® T-VOL and the SIz S-VOL (secondary volume) are shared.
- The FlashCopy® T-VOL and the SIz P-VOL are shared.
When you use FlashCopy® volumes, there are some SIz pairs that cannot be created. These are shown in the following diagram.