A specific scratch pool is a repository of empty tapes restricted for use by a specific user or set of users. When DFSMShsm is in a specific scratch pool environment, each empty tape as well as each used tape is known to DFSMShsm as a result of being added to the scratch pool, generally by the ADDVOL command. These tapes can be used by only DFSMShsm. The key ingredient of a specific scratch pool is that when an DFSMShsm tape becomes void of data, it is not returned to the global scratch pool but it is retained by DFSMShsm in the specific scratch pool for reuse by DFSMShsm. (You can think of "HSMTAPE" as identifying the pool of specific scratch tapes managed by DFSMShsm.)

Specific scratch pools are not recommended; they are used generally where tapes are owned by individual groups and hence restricted to that group's use, or where the customer’s tape management product cannot manage DFSMShsm’s tape usage otherwise. These restrictions cause the existence of several mutually exclusive sets of tape and hence increase the size of the overall tape pool as well as the complexity of handling them. When tapes are entered into specific scratch pools of an SMS-managed tape library, ensure that they are assigned a PRIVATE status and that they are associated with the appropriate storage group.

You can determine which tapes are in a specific scratch pool (these are your site’s specific scratch tapes) by issuing the LIST TTOC SELECT(EMPTY) command as discussed in Looking at your tape library with the LIST command and in the z/OS DFSMShsm Storage Administration.

For more information about the role of scratch pools in tape processing, see Figure 1. For more information about the various scratch pool environments, see Selecting a scratch pool environment.

Figure 1. Overview of Tape Scratch Pools. A global scratch pool does not require making tapes known to DFSMShsm because they are managed by a tape management product (DFSMSrmm, for example). Global scratch pools are recommended for SMS-managed tape libraries and unattended operation.

Because DFSMShsm records specific scratch pool activity in the control data sets, a specific scratch pool requires that the operator make tapes known to DFSMShsm by adding tapes to the scratch pool with the DFSMShsm ADDVOL command and by deleting tapes with the DFSMShsm DELVOL command. Specific scratch pools are recommended for nonlibrary environments where specific tapes must be kept physically separate from each other.