CMMVC9757E The command failed because there are legacy FlashCopy mappings using one or more of the volumes as a source VDisk.

Explanation
 Adding snapshots to volumes that are source volumes of legacy FlashCopy mappings will result in
restricted usability of the legacy FlashCopy mappings.

User response
Retry the command specifying the correct set of volumes or override this check to accepted
restricted legacy FlashCopy functionality.