Three times in the past month, our VM ADSM server has run out of
recovery log space, which is not at all a pretty sight.  After the
second occurrence of the problem, I doubled the recovery log space
from 56M to 112M (200 cylinders of 3380).  This kept us going for
a couple of weeks, but we had the failure again last night.

I have a virtual machine that watches over DSMSERV.  As the result of
the first two failures, it has code to do a QUERY LOG every ten minutes.
I am seeing the percent utilization for the log usually under 2%, but
every once in a while it goes shooting up to 50% or more.  Then, it
will suddenly drop down to the normal value in one of these 10-minute
intervals.

My current hypothesis is that the problem is the result of a migration
from BACKUPPOOL (disk) to tape, but I'm not sure of this.  Can anybody
tell me what ADSM saves in the recovery log during this process?  I'm
guessing it must be an entry for every file that is moved.

We had a migration going yesterday from 15:27 until the log filled up
at 00:32.  During that period, I saw the log utilization bouncing up
and down.  It was 2.8 at 22:42, for example, although it had been much
higher earlier.

The day before that, we had a migration going from 22:16 to 00:52, but
the utilization got up to "only" 50.6 percent, starting from 0.5 just
before the migration began.  Between 01:22 and 01:32, it dropped from
50.4% to 0.4%.  I'm not sure that migration was the process involved,
but there were no other long-running processes.

I'm ready to throw another 100 cylinders at the problem, but I'm not
at all sure that something pathological isn't going on here.  I'm also
worried that I've lost information (or tapes) as the result of shutting
the server down after the failures.  Advice?

Melinda Varian,
Princeton University