Management class considerations

The ABARS aggregate group definition can contain a management class name that is used to obtain a management class definition. Use the management class definition to determine the following aggregate backup parameters:

The maximum number of aggregate group backup versions to be kept (a specific number of versions up to 9999, or NOLIMIT).
Note: Specifying a limit allows the creation of a new version to roll off (delete) all existing versions that exceed the current limit.
NOLIMIT specifies that no roll-off occurs.

Aggregate group backup RETAIN parameters for ABACKUP versions:

  RETAIN ONLY VERSION = DAYS  |  WEEKS | MONTHS | YEARS(nnnn) | NOLIMIT

  RETAIN EXTRA VERSIONS = DAYS  |  WEEKS | MONTHS | YEARS(nnnn) | NOLIMIT

Note: These values do not affect the expiration date on the actual tape labels.

The serialization option:
```
  COPY SERIALIZATION = C | F | blank
```
Specify C (continue) for “tolerate an enqueue failure”, and F (fail) for “do not tolerate an enqueue failure”. Blank means a null entry.
The ABACKUP COPY TECHNIQUE. You can specify:
PREFERRED (P)

A concurrent copy session is requested for each data set. The aggregate backup continues if a concurrent copy session is not obtained for a particular data set.

REQUIRED (R)

A concurrent copy session is requested for each data set. The entire aggregate backup fails if a concurrent copy session is not obtained for a particular data set.

STANDARD (S)

A concurrent copy session not be requested (default).

VIRTUAL PREFERRED (VP)

A virtual concurrent copy session is requested for each data set. The aggregate backup continues if a virtual concurrent copy session is not obtained for a particular data set.

VIRTUAL REQUIRED (VR)

A virtual concurrent copy session is requested for each data set. The entire aggregate backup fails if a virtual concurrent copy session is not obtained for a particular data set.

CACHE PREFERRED (CP)

A cache-based concurrent copy session is requested for each data set. The aggregate backup continues if a cache-based concurrent copy session is not obtained for a particular data set.

CACHE REQUIRED (CR)

A cache-based concurrent copy session is requested for each data set. The entire aggregate backup fails if a cache-based concurrent copy session is not obtained for a particular data set.

Note: Use these additional considerations when using cache-based concurrent copy to process large data sets or volumes, or when using multiple tasks to process a large number of data sets:

Use concurrent copy only during periods of light update activity for the data sets or volumes involved.
Spread multiple concurrent copy jobs across as many LPARs as possible.
Ensure that jobs and address spaces that will use concurrent copy are assigned a WLM service class with a high execution velocity. Never assign a discretionary goal to concurrent copy work.
Ensure that volumes that will be processed will not be reserved by another system during the concurrent copy.

In addition:

DFSMShsm generates a default expiration date of 99365 for the ABARS output files. (Installation exit ARCEDEXT is called, if active, to allow you to specify expiration dates such as 99000 that have special meaning to tape management products).
When rolling off an ABARS version, DFSMShsm expires tape data sets without regard to the tape expiration date.
DFSMShsm saves the management class name in the ABR record so that EXPIREBV can obtain the latest retain values.

Note:

If the management class specified in the aggregate group definition does not exist, ABACKUP fails.
If a management class is not specified in the aggregate group definition, ABACKUP continues using the default management class. If a default management class is not defined, ABACKUP uses the following DFSMShsm defaults:
- RETAIN ONLY VERSION = NOLIMIT
- RETAIN EXTRA VERSIONS = DAYS(14)
- NUMBER OF VERSIONS = 2
- COPY SERIALIZATION = STATIC
- ABACKUP COPY TECHNIQUE = STANDARD
The default management class name is never stored in the ABR record.