The BCS can be maintained independently from the data sets cataloged in it.

The dynamic information associated with a catalog data set (the data set characteristics) resides in the VVDS on the same volume as the catalog data set itself. The VVDS contains the data set characteristics that must be synchronized with the data set each time it is updated. Therefore, you can copy the data sets or the volume periodically for backup and recovery without causing the data set and VVDS portion of the catalog to be out of synchronization.

Information that can be out of synchronization in the catalog (for example, a frequently used relative byte address on volume and extents) is moved from the catalog to the VVDS. The VVDS resides on the same volume as the data set component. Therefore, you can back up data sets independently of the BCS.

The BCS maintains a record of the associated data sets with a sphere record. For example, the sphere record contains a record of a base cluster and its related alternate indexes. All the objects associated with the sphere record are processed before the sphere record is updated. You can therefore restart most processing at the point of interruption, without losing data or special processing.

You can also use the Integrated Catalog Forward Recovery Utility (ICFRU) to recover a damaged catalog to a correct and current status. This utility uses system management facilities (SMF) records that record changes to the catalog, updating the catalog with changes made since the BCS was backed up. ICFRU can also be used with shared catalogs or master catalogs, if the master catalog is not being used as a master at the time.