ADSM-L

Re: Client Session Stuck in MEDIAW Status During Migration

1998-03-18 11:43:45
Subject: Re: Client Session Stuck in MEDIAW Status During Migration
From: "Thomas A. La Porte" <tlaporte AT ANIM.DREAMWORKS DOT COM>
Date: Wed, 18 Mar 1998 08:43:45 -0800
I've seen this situation occur with our disk pools as well. What
seems to happen is a) the disk pool fills up (100% or very near
to it), b) migration begins, c) sessions targeted for the filled
disk pool now need to go to tape, b/c disk pool is full, so they
go into MediaW state.

Once (c) has happened, and the session has requested a tape,
there seems to be no going back to the disk pool for that
session, even if migration brings you back down to 0%
utilization.

I'd like to see this changed such that the session will
reconsider the disk pool once migration has brought it down under
the "High Migration %" value.

 -- Tom

"It's a dog eat dog world,                Thomas A. La Porte
 and I'm wearing milkbone underwear."     DreamWorks SKG
              - Norm Peterson             <tlaporte AT anim.dreamworks DOT com>

On Wed, 18 Mar 1998, Jeff Connor wrote:

>I have a problem that comes up from time to time that I was wondering if
>anyone else has experienced the same thing during disk to tape storage pool
>migrations.  My ADSM environment is as follows:
>
>ADSM MVS Server V2.1.10 running on OS/390 V1R2.
>TCPIP for MVS V3.2
>Client is HP-UX V10 running V2.1.6 of the ADSM Client
>80GB disk storage pool migrated to Magstar 3590's in an STK Silo daily by
>setting hi and lo thresholds to zero.
>Disk pool migration thresholds are set at hi=95 lo=75 during the night.
>
>The scenario is our disk pool fills up during the nightly backups and
>migration begins.  Last night we got as high as 99.2% utilized while
>migrations were running.  The problem, aside from having a disk pool that
>is currently undersized, is that some client backup sessions show a status
>of mediaw indefinitely.  I can understand that occurring initially when the
>disk pool is 99+% full.  I mean hey there's no place for the data to go
>right?   The problem is that even when the pool utilization drops to say
>under 60% the sessions that showed mediaw still are stuck/not running still
>showing a status of mediaw even though there appears to be plenty of space
>available in the disk pool.  Does anyone know why these sessions are
>hanging in a mediaw state and don't just start running as space becomes
>available as data migrates from disk to tape?  I thought of setting the
>high migration value to a lower number like 80 for example thinking that if
>migration started before we reached such a high utilization factor  it
>might avoid the apparent "gridlock".  Even if that fixes the problem it
>still doesn't explain why the sessions hang in mediaw state indefinitely
>and have to be eventually canceled even though space does become available
>as data is migrated.  Any ideas?
>
>Jeff Connor
>Niagara Mohawk Power
>Syracuse, NY
>