A consistency group is a group of pairs on which copy operations are performed simultaneously and in which the status of the pairs remains consistent. A consistency group can include pairs that reside in up to four primary and secondary systems.
You can issue a TrueCopy command to a consistency group to perform the operation on all pairs in the group at the same time. The status of the pairs changes at the same time, though this depends on the group options you have set. Some pair operations take priority under certain circumstances. For details, see Consistency group planning.