All XRC secondary volumes must stay dedicated exclusively to XRC use. It is recommended that you make the secondary volumes offline and unavailable to other host systems, but not to the system data mover, thereby ensuring that no write I/O operations occur outside the SDM function. You can do this by making the volumes part of a system-managed, disabled storage group, and by keeping the volumes offline to all but the SDM system. Ensure the data integrity of the secondary volumes by not allowing other functions to make updates to them.
Secondary volumes may have data read from them while they are in an XRC session. However, if primary system programs change the VTOC pointers, data can appear to have been copied improperly when read from another system. To avoid this, refresh the in-storage system pointers by varying the secondary volumes off and then on to the system that is reading from the volume. Allow the volumes to reach duplex state before doing this refresh operation.
For additional information about storage groups, refer to the z/OS DFSMSdfp Storage Administration.