VM:Tape TMC fields BLKSIZE and BLKCNT.
TMC fields BLKSIZE and BLKCNT are not populated for tapes created on z/VM by VM:Backup, HiDRO and VM:Archiver.
These fields have a value of zero. Is it possible to enable the fields to be populated?
Tapes created by VM:Backup, HiDRO and VM:Archiver.
VM:Backup, HiDRO and VM:Archiver do not populate the BLKCNT and BLKSIZE fields when they write data to tapes managed by VM:Tape. Those fields do get populated in z/OS though. No matter what type of TMC it is, CMS does not provide facilities for capturing block counts, block sizes and VM:Tape does not maintain them.
You may want to consider implementing VM:Tape's USERACNT user exit which is called by the MOUNT command and will initialize or modify local site-defined fields in the accounting area of the TMC record. The accounting area is field ACCT and is 50 bytes long. .