To add on to Lizette's comments and using her example below, if vol1-4 are in a
connected set (i.e. continued volumes), *ALL* volume in the connected set must
meet the threshold or *NONE* will be selected for recycle.
E.G. the connected set consists of 4 volumes.
VOL1 50%
VOL2 20%
VOL3 15%
VOL4 1%
Any RECYCLE PERCENTVALID < 50 will result in *NONE* of the volumes being
selected for recycle. There are 2 ways around this.
1) Break the connection by recalling/deleting the "spanning" dataset. This
dataset can be found by HSEND LIST TTOC(volume) and will either be the 1st or
last dataset listed and recycle the "disconnected" volume.
2) Run RECYCLE EXECUTE VOLUME(any volume in the connected set). This will cause
any gaps in the connected set to be eliminated and all of the tapes in the
connected set will *APPROACH* 100% utilization. This may or may not release one
or more tapes from the connected set. In the example above this would result in
1 volume of 86% instead of 4 volumes with an average utilization of 22%.
There are a number of SETSYS parameters in addition to PARTIALTAPE(MARKFULL)
that affect this as well.
There is more to this topic than can be covered in a short email.
I suggest reading the DFSMS/hsm Storage Administration guide:
SC23-6871-02 z/OS DFSMShsm Storage Administration (z/OS 2.1).
HTH,
<snip>
PARTIALTAPE(REUSE) vs PARTIALTAPE(MARKFULL) When using a virtual tape system,
IBM usually recommends using PARTIALTAPE(MARKFULL).
RECYCLE
You (or automation) need to issue the RECYCLE command, it is not automatic.
Also, if you want HSM to recycle multiple tape volumes onto one, you will need
to use a GENERIC recycle command, for example:
Use 'ALL' to recycle both ML2 and backup tape volumes:
HSEND RECYCLE ALL PERCENTVALID(20) EXEC
Use 'ML2' to recycle only ML2 tape volumes:
HSEND RECYCLE ML2 PERCENTVALID(20) EXEC
Use 'BACKUP' to recycle only backup tape volumes:
HSEND RECYCLE BACKUP PERCENTVALID(20) EXEC
Suggested numbers for ML2RECYCLEPERCENT are 20% or 30%. This allows more
volumes to become eligible to be recycled onto fewer volumes at the same time.
For example:
VOL1 50%
VOL2 20%
VOL3 15%
VOL4 1%
With ML2RECYCLEPERCENT(1), only VOL4 will be recycled. The next time you run
RECYCLE again, the same tape would be recycled again and again. With
ML2RECYCLEPERCENT(25), VOL2, VOL3 and VOL4 would be recycled. The resulting
percent used for the output tape will become 36%, so, that tape will not be
recycled again the next time around.
MAXRECYCLETASKS(nn). Each recycle task requires an output tape. If you allow
5 recycle tasks to run concurrently and have 5 tapes to recycle, you will land
up with 5 recycled tapes (no reduction). If you increase the time between
recycles, this should also allow more tapes to become eligible to be recycled
onto fewer tapes.
If you have migrated to a new tape technology, the REUSE CAPACITY (this is an
average) will be incorrect leading to unneeded recycles. With time however,
the REUSE CAPACITY will better reflect the reality of your new environment.
</snip>
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