Through the CBRXLCS FUNC=QVR programming interface, TVIVCOPY can be used to determine if there is at least two valid copies of the logical volume in a multi-cluster grid configuration. However, this single bit indicator cannot be used to determine in which distributed libraries (or clusters) a copy exists. So for multi-cluster grids (beyond two), this single bit does not return enough detailed information. Starting with Release 2.1 of the TS7700 Virtualization Engine, TVICCMAP can be used (1-byte copy cluster bit mapping) that will indicate in which clusters, a valid copy of the logical volume exists. The cluster bit mapping is ordered left to right with the first bit representing cluster 0, the second bit representing cluster 1, etc. If a particular cluster is missing from the configuration (skipped) that bit position will remain OFF”. The bit positions match how the clusters are defined in the configuration (by cluster number starting with cluster 0) and are positional. The validity of TVIVCOPY and also TVICCMAP is based on the availability of each cluster in a TS7700 multi-cluster grid so if one or more of the clusters are not available (and cannot be queried), the bit indicators may not be appropriately reflected. The new copy cluster bit mapping (TVICCMAP) is returned at TS7700 Release 2.1 (or later). Before using the new copy cluster bit mapping (TVICCMAP), status flag TVICCMOK should be checked to ensure that the new bit mapping is valid to use.