ADSM-L

Re: tape libraries

2000-04-05 16:47:24
Subject: Re: tape libraries
From: Gerald Wichmann <gwichmann AT SANSIA DOT COM>
Date: Wed, 5 Apr 2000 13:47:24 -0700
* What happens if someone kicks off a restore that requires a tape and both
> tapes are being used (if they=92re both being used) as in the above insta=
> nces?
> I=92m assuming the higher priority process (restore) halts the
> migration/reclamation like it does on a single drive library and grabs a
> drive=85?
Yes but - if a tape is being reclaimed, you may see a forty-minute wait
before TSM gives up the drive!  Better to leave one drive free for
restores.


Is this due to the default 60 minute mount retention? I.e. reclamation as a
process stops, but the tape it was reclaiming remains mounted in the drive
until TSM unmounts it.
Which brings to mind the question of mount retention.. I know 60 is default
but I've ran into numerous situations where something didn't run or hangs
for a long time because my tape library had a tape mounted in it's drive
essentially doing nothing (IDLE). What are the cons to lowering mount
retention to something more reasonable like 5 minutes? Or for that matter
why not 1 minute? If it's not doing anything may as well unmount it I say!
Thanks,
Gerald
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