When one or more volumes are added to a storage group within a copy pool, DFSMShsm includes those new volumes with any subsequent backup versions. If you must recover a version that does not contain the new volumes, and data has been placed onto those volumes, after the recovery, those volumes will contain residual data that is unusable and must be cleaned up.
Example: If you have a storage group that has 2 volumes (volumes A and B) and you request a fast replication of those two volumes. Later on, you add a third volume (volume C) to the storage group. New data is then placed onto volume C. You discover that an error has occurred and that you need to recover the last backup version. During the recovery, volumes A and B are recovered to the point of the fast replication. Because volume C was not a part of the original fast replication backup, it is not processed during the recovery. Volume C may contain data that is no longer valid and you will need to review this data on the volume. DFSMShsm issues message ARC1810I for each volume that fits this scenario.