Draft Document for Review February 7, 2020 3:15 pm 8464ch02_Architecture.fm If you do not specify the Retain Copy Mode, the copy policies from the mount cluster are  refreshed at mount time. When clusters do not agree on MC settings, this issue can result in  more copies being made that were not intended because the consistency points can change  with each mount.  DAA often prevents such conditions, but it is still recommended to enable Retain Copy Mode  when peers do not have identical MC settings. Existing copies are not removed if they are  present. Remove any non-required copies by using the  LIBRARY REQUEST REMOVE  command. If a virtual volume is modified during a specific mount operation, it is premigrated to back-end  tape or cloud (if present) and has all copy policies acknowledged. The virtual volume is  transferred to all defined consistency points.  If no modification occurs while the volume is mounted, the TS7700 does not schedule another  copy operation and any current copy of the logical volume on a stacked volume or in the cloud  remains active. Furthermore, copies to remote TS7700 clusters are not required if  modifications were not made No differences exist between LWORM in multicluster and stand-alone cluster environments.  The LWORM behavior for any logical volume is consistent across all clusters in the grid. 2.4.13 Logical WORM support and characteristics 2.4.14 Virtual drives From a technical perspective, no differences exist between virtual drives in a multi-cluster grid  versus a stand-alone cluster. Each cluster has 256 drives per default (see Table 2-1). Table 2-1 Default number of maximum virtual drives in a multi-cluster grid Cluster type Number of maximum virtual drives Stand-alone cluster 256 Dual-cluster grid/Two-cluster grid 512 Three-cluster grid 768 Four-cluster grid 1024 Five-cluster grid 1280 Six-cluster grid 1536 Seven-cluster grid 1792 Eight-cluster grid 2048 72  IBM TS7700 Release 5.0 Guide