To define the environment to use the capacity of IBM® tape drives that emulate IBM 3490 tape drives, you must perform the following steps:

1. Define an esoteric to MVS™ that only contains IBM tape drives emulating IBM 3490 tape drives with the extended capacity support (CAPACITYMODE switchable). All of the drives within an esoteric must use the same recording technology.
2. Vary online the drives that are CAPACITYMODE switchable after any IPL.
3. Use the SETSYS USERUNITTABLE command to define the new esoteric to DFSMShsm. Be sure to provide an input translation unit so a non-CAPACITYMODE switchable unit is not selected by default.

   Example: When you specify the SETSYS USERUNITTABLE(es1, es2out:es2in,es3cupe:es3cupe) command, the esoteric unit name es3cupe is identified to DFSMShsm as valid. Since the same esoteric unit name is specified for both input and output, the same units are candidates for input and output allocations. Substitute your esoteric name for es3cupe.

4. Use the SETSYS TAPEUTILIZATION(CAPACITYMODE(EXTENDED | COMPATIBILITY) UNITTYPE(new esoteric) PERCENTFULL(nn)) command to tell DFSMShsm how to use the drives in that esoteric.
5. Use the appropriate DFSMShsm commands to define for output, the new esoteric to DFSMShsm functions, like BACKUP or MIGRATION.

   Example: You can use the SETSYS backup command for backup functions or the SETSYS TAPEMIGRATION command for migration.

Note: You can only use the 3592 Model E05 and newer tape drives only in 3590 emulation mode; never 3490. The 3592 Model J1A can operate in 3490 emulation mode only when using MEDIA5 for output.