Understanding tape mounts and free pools

There are two basic types of tape mounts: scratch and volume-specific mounts. You specify the type of mount with the TAPEMNT command when you request the mount.

Only volume-specific mounts are allowed for tapes in the System Pool, and the requestor must be a system administrator. Normally, a mount from the System Pool would be for the purpose of reviewing the contents of a tape or for some other administrative purpose. The status of a tape in the System Pool is not changed, e.g., the status of the tape is not set to USED when it is mounted.

Mounts for private pools may be either scratch or volume-specific mounts. If a private pool contains a suitable scratch tape, the scratch mounts are filled from the private pool. If a private pool does not have a suitable scratch tape, a scratch mount will fail unless the private pool has a FREEPOOL association, in which case the free pool will be examined to locate an appropriate volume. A volume from the free pool will be moved to the private pool for which the scratch mount was requested.

The free pool can be specified when the private pool is defined, or it can be specified later using the POOLMOD command. A free pool can be specified as either the system free pool (FREEPOOL SYS) or as a private pool (FREEPOOL pool_owner pool_name).