OK, last post from me on this subject to give the solution.
The problem was some resource shortage, most likely a thread limitation,
software or hardware.
Once we reduced our storage pool volume count to under 1,700 TSM was
able to handle its workload of 300+ peak concurrent sessions.
We reduced the number of volumes, not the total size of the pools.

For comparison the header on Show Thread is:
Thread table size:  3136
Active threads:     1741
Zombie threads:     0
Cached descriptors: 3

The fatal number of active threads for this system is about 2,100.  This
was taken with the system basically at idle.

Thanks Mr. Sims for providing the needed nudge in the right direction.


Andy Huebner
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Richard Sims
Sent: Monday, January 09, 2006 9:25 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Primary disk pool volume limit

On Jan 8, 2006, at 9:06 PM, Andy Huebner wrote:

> ...
> When I do a show thread there is a line that is "Thread table size". I
> am assuming that is a thread limit of some sort.  Do you know if
> this is
> correct?

It would seem to be TSM's personal choice for a table which manages
thread information. There's no doc on this that I know of, but may be
the table in which TIDs area created in pthread_create() operations.
We don't know if it is of fixed size, or whether TSM may reallocate
it if the table needs to be larger. My hunch is the latter.

FYI, here's a snapshot of mine, at a time when the server is busy
with backups:

Thread table size:  128
Active threads:     94
Zombie threads:     0
Cached descriptors: 5

>
> I have reduced the storage pool volume count by about 150 and TSM was
> able to handle more sessions before it would no longer accept
> connections.  This makes we believe that there is some sort of
> limit on
> the number of threads that is well below the AIX 5.1 limit.  This
> limit
> may be something doing with available RAM or some other cause.  I do
> think I inadvertently found the cliff and jumped...

A thought: Threads space comes out of the Heap. When starting the TSM
server, assure that your memoryuse Unix Resource Limit is not
artificially low. (In csh and tcsh, see this with the 'limit' command.)

    Richard Sims


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