In previous releases, DFSMShsm treated all data in Level 0 (L0) as being in one single tier in the overall storage hierarchy, with no policies to enable automated data movement within that L0 tier. In this release, DFSMShsm is enhanced to move data from one class of devices to another within the L0 hierarchy. This process is called class transition. Because of this complexity, the full overview of this new enhancement is described in detail in An overview of storage tiers.
To allow DFSMShsm to migrate and back up larger data sets, the DFSMShsm limit of the number of tapes that a DFSMShsm migration or backup data set can span has been increased from 40 to 254. RECYCLE will now also process connected sets of up to 254 volumes.
The DFSMShsm MCD, MCC, and FSR records have been extended to contain up to 254 volumes. FSR records that list more than 144 tape volsers will be truncated when written to the DFSMShsm log data sets. This will affect the ARCPRLOG and ARCPEDIT output. The formatted dump of each FSR in the ARCPRLOG output will include only the portion of the FSR that was written to the log. When the output volsers included in an FSR for RECYCLE have been truncated, the ARCPRLOG and ARCPEDIT output will display "TOVOL=******".
A MIGRATIONSUBTASKS(YES | NO) parameter has been added to the SETSYS command. It allows DFSMShsm to run multiple subtasks concurrently under each migration task for primary space management, on-demand migration, and interval migration on level 0 volumes that migrate data sets to ML1 or ML2 volumes.
The ADDITIONALSUBTASKS(nn) subparameter allows you to dynamically change the number of additional subtasks that the system can use, running under each migration task. These additional subtasks add to the number of subtasks that the system already uses when the MIGRATIONSUBTASKS parameter is specified. Note that the actual number of total subtasks used can vary. In general, the total migration subtasks used will be lower if a large value is specified with the maximum migration tasks (MAXMIGRATIONTASKS) parameter. Conversely, the total migration subtasks used will be higher, up to 15, if a smaller value is specified with the maximum migration tasks (MAXMIGRATIONTASKS) parameter.
By processing data sets in migration subtasks for a level 0 volume migration task, the aggregate throughput of all the migration tasks is improved.
A NEWNAME(newdsname) parameter has been added to the FRRECOV command. It allows DFSMShsm to use a new, fully-qualified data set name for the recovered backup version or dump copy.
DFSMShsm fast replication data set recovery will no longer be restricted to recovering data sets back to the original volumes. If DFSMShsm is not able to recover a data set to the original volumes, it will instead select the most eligible volumes with the most free space within the storage group. There are no changes to the DFSMShsm commands.
DFSMShsm fast replication backup will now support FlashCopy consistency groups. A new FlashCopy consistency group option will be added to the SMS copy pool definition. If set to 'Yes' for the copy pool, it indicates that the copy pool backup version must be data-consistent. If the FlashCopy consistency group function fails, the FRBACKUP command will be terminated and the new or in-process copy pool backup version will be invalidated. The FlashCopy consistency group option can be used in combination with other FlashCopy options.
For more information, refer to the topic covering Defining copy pools in z/OS DFSMSdfp Storage Administration.
A ZCOMPRESS parameter has been added to the DEFINE DUMPCLASS command. It allows DFSMShsm to specify whether to use zEDC Services on the dump data.
A ZCOMPRESS parameter has been added to the SETSYS command. It allows DFSMShsm to specify the type of compression used during migration or backup for all data sets.