I see this happen sometimes too.  Yesterday I was doing an incremental
backup, and on a file that about 600,000 bytes it said it was waiting for a
tape mount.  The disk storage pool was only around 30% used and I have the
maxsize set to 100M.  Nothing else was going on in ADSM.  No other backups,
nothing.

Tina

> -----Original Message-----
> From: Bill Colwell [SMTP:bcolwell AT DRAPER DOT COM]
> Sent: Friday, November 20, 1998 12:53 PM
> To:   ADSM-L AT VM.MARIST DOT EDU
> Subject:      Re: Why are tape mounts being requested?
>
> In
> <0F672B7FF23CD211A41500A0C9CFE0FA27F195 AT ffxexcluster1.co.fairfax.va DOT 
> us>,
> on 11/20/98
>    at 11:19 AM, "Nichols, Linnea" <linnea.nichols AT CO.FAIRFAX.VA DOT US> 
> said:
>
> >I'm pulling my hair out over this one and hope someone can help. I am
> >getting tape mounts at night while clients are backing up and can't
> figure
> >out why. I'm running the MVS server at 3.1.2. I'm doing a "query process"
> >every hour, and it shows that there are no processes running. At the time
> >the tape mounts occur, migration thresholds are set to 95 80, and there
> are
> >no migration messages appearing. Space reclamation on both my onsite tape
> >and copy tape pools are much earlier, and are to be completed 4 to 5
> hours
> >earlier than these tape mounts occur. All of my "maximum size file"
> limits
> >on my storage pools show as "no limit".
>
> >From doing a "q content" and "q vol" on the tapes, it looks like the
> >backups from some of my clients are going directly to my tape pool, and
> NOT
> >to my DASD pool, but for the life of me, I can't figure out why!!
>
> >Am I doing something wrong or something stupid? Or should I log this as a
> >problem with IBM support?
>
> >Linnea Nichols
>
> >Fairfax Co. Govt, Fairfax, VA    Linnea.Nichols AT co.fairfax.va DOT us
> >Phone:703/324-2708                FAX: 703/324-3931
>
> Try doing a 'q ses f=d' periodically in addition to 'q proc'.  This will
> show what nodes are using tapes if any.
>
> Are you using caching on the diskpool?  This complicates the search for
> free
> space to hold new backups.  I suspect that the freespace in your diskpool
> is
> very fragmented and when the server is looking for room to hold a file
> that
> the client says is big, it can't find enough space in a limited number of
> pieces.  There may be an undocumented limit to how many pieces of
> freespace
> can be put together for use by one aggregate.  Or it may be a bug.
>
> You could try running the pool at 85 70 instead of 95 80 to see if the
> problem goes away.  Another trick would be to empty one of the volumes in
> the diskpool by doing a move data on it.  then you will have  big chunk of
> unfragmented free space.
> --
> -----------------------------------------------------------
> Bill Colwell
> C. S. Draper Lab
> Cambridge, Ma.
> bcolwell AT draper DOT com
> -----------------------------------------------------------