The functional enhancements available with z/OS® V21R1 DFSMSrmm provide you with these benefits:
- DFSMSrmm operational enhancements
- Retain data sets based on the number of days since they were
last referenced: Data sets managed by the EXPDT retention method
can be retained or expired based on the number of days since the data
set was last referenced. A new LastReferenceDays attribute is added to the data set record as a binary number.
The value is taken from the new LASTREF suboperand of the DFSMSrmm
parmlib OPTION RM(EXPDT) operand
If the volume set is retained
by SET or VOLUME the LastReferenceDays data set attribute will be
kept equal for all files of a multi-volume data set. The latest LastReferenceDays update to a single file in a
multivolume data set is propagated to all files that belong to the
same multi-volume data set. However, for volume set retained by FIRSTFILE
the LastReferenceDays data set attribute
will be set but not equalized across the multi-volume data set because
the expiration date depends only of the first file of the first volume,
and its LastReferenceDays.
The
LastReferenceDays value can be:
- Set by the ADDATASET subcommand when the data set record is created
- Changed by the CHANGEDATASET subcommand any time after the data
set record has been created.
- EXPDT retention method now allows retention to be based on
a single volume or volume set, or on a controlling first file: You now have the option of retaining volumes with the EXPDT retention
method based on a single volume or volume set, or on a controlling
first file. The parmlib OPTION RM(EXPDT(RETAINBY(VOLUME/SET/FIRSTFILE)))
can specify:
- RETAINBY(VOLUME)
- DFSMSrmm expires volumes in a multi volume set at the volume level.
Each volume has its own expiration date. RETAINBY(VOLUME) is the default
value.
- RETAINBY(SET)
- DFSMSrmm expires volumes in a multi volume set at the volume set
level. All volumes in the set have the same expiration date, which
is the maximal expiration date of all volumes (except if changed by
the CV command).
- RETAINBY(FIRSTFILE)
- DFSMSrmm expires volumes in a multi volume set at the volume set
level. All volumes in the set have the same expiration date, which
is the expiration date of the first file in the volume set (here a
single volume is treated as a volume set with only one volume in it).
You can also set the RETAINBY for a specific volume
set by subcommand. Note: These new options apply only to the EXPDT
retention method, not to the VRSEL expiration method. The processing
of volume sets managed by the VRSEL retention method is unchanged.
- DFSMS Management Class attributes: You can now set the
expiration date in DFSMSrmm for a tape data set with a DFSMS Management
Class (MC). When you enable use of MC attributes by DFSMSrmm, the
MC expiration attributes (except the MC Expiration attribute Retention
limit) are retrieved by DFSMSrmm during OPEN for output and used to
set the expiration date for the tape data set, and also to set the
LASTREF extra days in the tape data set record on retention method
EXPDT managed volumes. Regardless of whether the expiration attributes
are retrieved from MC, from a DFSMSrmm default parmlib option or from
an installation exit, an expiration date is calculated and will be
used to manage expiration. Any attributes needed to continue management
of retention, such as ‘days non-usage’ are bound to the data set record
in the DFSMSrmm CDS, depending on the retention method. This is a
one-time action, thus avoiding any overhead of repeating the policy
decisions as part of inventory management. At OPEN for input the MC
attributes are not considered for processing. At OPEN for output with
Disposition MOD the MC attributes are not considered for processing.
The enablement in DFSMSrmm provides options to use or not use these
MC attributes for all volumes, and it provides an option for VRSEL
managed volumes to exclude the MC attribute ‘Expire after Date/Days‘.
This last option is recommended if it is desired that the processing
of VRSEL managed volumes not change with DFSMSrmm V2R1.
The Management
Class expiration attributes processed by DFSMSrmm are:
- Expire after days Non-usage, which is equivalent to LASTREF extra
days
- Expire after Date/Days, which is equivalent to expiration date
/ retention period.