To split a ShadowImage for Mainframe pair, issue the PPRC CSUSPEND command or the PPRCOPY PPRCOPY SUSPEND command to the P-VOL of the pair.
When you issue the command, the volumes must have the DUPLEX status (pair create or Quick Resync has been performed).
For pairs in the DUPLEX status, the P-VOL and its associated S-VOLs are typically not identical since update copy operations are performed asynchronously. When you split a pair and the volume status changes to Split/SUSPOP status, the host can access the S-VOL. When the pair status is not Split/SUSPOP, the host can access a non-reserved S-VOL. The host cannot access reserved volumes that are unpaired.