Hello,
well, your theory sounds right for apar PQ18693 (MVS server)
but the problem exixts for other server platforms as well.
What happens is that the same tape gets reselected again at EOV.
What you would see in the activity log would be ANR5321I followed
by ANR0530W.
There is no official fix for this yet. It should be fixed in the next level
of the server to come out soon. For now, you can turn collocation off
temporarily until ADSM selects another volume for this client and you
can then turn collocation back on after.
Good day !

Rejean Larivee
ADSM Level 2 Support



> I have the same problem with some HP-UX clients.. It seems to occur when my
> disk pool is 100% full and data is migrating to tape.. I can restart the
>
> I have been seeing the following error a lot since we upgraded to Version 3
> and beyond (currently, we are running 3.1.1.5 server level) The error is:
>
>         ANS1301E Server detected system error

I see a lot of these too for unix clients.  It appears to me that they
occur when the client is backing up directly to tape, and the tape hits
EOT.  Rather than close out that tape, and grab another, the backup fails.
Then, when migration fills that tape, and the client gets a new tape
(colocation), the next backup completes successfully.  I have not
reported this to IBM, as I have been busy persuing other ADSM defects, and
this is only my theory.

Steve (unVMix Systems Programmer/Dude) Roder
(tkssteve AT ubvm.cc.buffalo DOT edu | tkssteve AT acsu.buffalo DOT edu | 
(716)645-3564 ,
   | http://ubvm.cc.buffalo.edu/~tkssteve)