"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 12/28/2005
10:28:53 AM:
> I am just starting with mainframe tape management using SMS and CA-1. We
> are running two production servers with Tivoli Storage Manager Version
5,
> Release 2, Level 3.0 on the same z/OS 1.4 LPAR.
>
> Our problem is with the Sequential Access Storage Pools on TSM, are not
> giving back reclaimable space on our tape pools.
> Most of our volumes are reporting volume status full even with
reclaimable
> space on the volume.
The "full" status of a tape has nothing to do with how much of the tape
has useful space; it is an indication that the tape, at some point in
time, has been filled to capacity. Once a tape reaches full status, status
will remain "full" until the tape is entirely reclaimed.
> Some of the full volumes are reporting as little as 15% utilization.
> We are running reclamation on the Storage Pools but, it is bringing back
> one or two volumes available out of over 300 tapes with at least 10%
> space.
What's happening here (at least with copy storage pool tapes) is that
TSM's reclamation process does not work from least full to most full; the
choice of what data to actually move during a reclaim of a copy pool tape
is convoluted and not particularly relevant here.
Here's an example. Here is a list of copy pool tape volumes:
A00001 10% full
A00002 22% filling
A00005 39% full
A00003 47% filling
A00004 99% full
If you set reclamation for this copy storage pool to 70, and assuming all
of these tapes' access is OFFSITE, tapes A00001, A00005, and A00002 are
eligible for reclaim. However, the data on those tapes will be moved
(reclaimed) in the order in which the data resides on the primary tape
pool that is used during reclamation. After an hour of reclamation, you
might see this:
A00005 7% full
A00001 10% full
A00002 11% filling
A00003 47% filling
A00004 99% full
This can be frustratingly slow, and can create a plethora of tapes with
very little left on them. What you should do to get more bang for your
time and resource buck is create a script that:
1. sets the reclamation level to 99
2. checks to see if this kicks off a reclaim action
3. if not, set the level to 98
4. checks to see if *this* kicks off a reclaim action
5. if not, set the level to 97
and so on. (This can be done prior to TSM 5.3, but is very easy to do in
5.3, since we now have a RECLAIM STG command with a WAIT=YES option.)
--
Mark Stapleton (mark.stapleton AT usbank DOT com)
MR Backup and Recovery Management
262.790.3190
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