The Backstore Engine › Allocation Logic - CA MIM or IBM GRS Support

Allocation Logic - CA MIM or IBM GRS Support

There are different configurations for physical tape devices supported by CA Vtape, as follows:

• Sysplex environments using CA MIM or IBM GRS.

  In these environments, the physical tape devices are truly shared and all systems see them as ONLINE at the same time. If one system is using a particular physical tape, CA MIM or IBM GRS will exclude it from allocations in all the other systems. This environment is automatically supported by CA Vtape if you specify the VTPARMS parmlib attribute BypassOfflinePhysicalDevices=Y (default value).

• Nonsysplex environments using CA MIM or IBM GRS to implement tape sharing.

  In these environments a pool of physical tape devices is shared between systems by keeping the physical devices in ONLINE status only in the system using it and in OFFLINE status in all the others. When allocations occur and the operating system finds all the required drives are OFFLINE, WTOR messages are sent to the console. In these environments, these messages are automatically replied to with WAIT/NOHOLD, which signals the sharing software to look for an unused physical tape device and vary it ONLINE in the system requesting the allocation. This environment is automatically supported by CA Vtape if you specify the VTPARMS parmlib attribute BypassOfflinePhysicalDevices=N.

• Nonsysplex environments where the physical tape devices are not shared.

  In these environments, each LPAR has dedicated physical tape drives in ONLINE status. This environment is automatically supported by CA Vtape if you specify the VTPARMS parmlib attribute BypassOfflinePhysicalDevices=Y (default value).