ADSM-L

Re: Tape drive recomendations

2002-11-01 11:52:25
Subject: Re: Tape drive recomendations
From: "Rushforth, Tim" <TRushfor AT CITY.WINNIPEG.MB DOT CA>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Fri, 1 Nov 2002 09:30:10 -0600
>From experience slow Offsite reclamation from Disk applies to DLT tape also.
It applies to all tape, it basically copies files one at a time.  See
IC15925.

-----Original Message-----
From: Mark Stapleton [mailto:stapleto AT BERBEE DOT COM]
Sent: October 31, 2002 5:23 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Tape drive recomendations

From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
Bill Boyer
> Be careful of your copypool reclamations with the disk cache turned on!!
> There is a BIG performance hit on reclamation when the primary copy of the
> file is on a DISK direct access storage pool. Then the MOVESIZETHRESH and
> MOVEBATCHSIZE values are thrown out the window and the files are processed
> one at a time.

This is true *if* LTO tapes are in the mix. Apparently the aforementioned
situation, in conjunction with the LTO backhitch process, makes for *slow*
reclamations.

> What I've done to relieve the restore times is to not MIGRATE the
> disk pools
> until the end of the day. That way restoring from last night is
> quick. I had
> a client where they wanted CACHE=YES on a 60GB disk pool. The offsite
> copypool reclamation ran for 2-days! Changed it so that migration
> started at 5:00pm and nobody complained about restore times.

You can also do a move data on the disk volumes. That will clear the cache
on an adhoc basis.

--
Mark Stapleton (stapleton AT berbee DOT com)
Certified TSM consultant
Certified AIX system engineer
MCSE

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