DFSMShsm checks the data set level attribute EATTR when performing
non-SMS volume selection. The EATTR data set level attribute specifies
whether a data set can have extended attributes (format 8 and 9 DSCBs)
and optionally reside in EAS on an extended address volume (EAV). The
EATTR attribute is optional. If you do specify it, valid values are
NO and OPT. For more information on the EATTR attribute, see ALLOCATE and DEFINE CLUSTER in z/OS DFSMS Access Method Services Commands.
If an EATTR value is not specified for a data set, the following
default data set EATTR values are used:
- The default behavior for VSAM data sets is OPT.
- The default behavior for non-VSAM data sets is NO.
Preference for volume selection corresponds to the EATTR values
for each data set:
- When EATTR = NO, the data set has no preference to any volume.
For recalls, recovers and ARECOVERs the volume with the most amount
of free space will be selected but only the track-managed free space
will be used for determining the free space calculations of an eligible
EAV. The data set will be allocated with a format 1 DSCB indicating
that it is not eligible to have extents in the EAS.
If an EAV or
non-EAV is chosen for allocation, and the value
is EATTR=NO and the data set had a format 8
or 9 DSCB with vendor attributes, then the data set is allocated with
a format 1 DSCB, and the system issues message ARC0784I to indicate
that extended attributes have not been retained for this recall, recovery
or ARECOVER. In this situation format 9 information of the data set
will be lost on the recall, recovery or ARECOVER.
- When EATTR = OPT, the data set will prefer EAV volumes if the
size of the allocation is equal to or greater than the BreakPointValue
(BPV) specified. If the requested size of the data set allocation
is smaller than the BPV then EAVs and non-EAVs will have equal preference.
- If an EAV is chosen for allocation and the data set type is EAS-eligible,
then the data set will be allocated with format 8 or 9 DSCBs in either
the track-managed space or the EAS.
- If a non-EAV is chosen for the allocation and the data set had
format 8 or 9 DSCBs with vendor attributes, then the data set will
be allocated with a format 1 and DFSMShsm issues message ARC0784I
signifying that extended attributes have not been retained for this
recall, recovery or ARECOVER. The EATTR value will always remain in
the format 1 DSCB.