ADSM-L

Re: Reclaiminig LTO Tapes

2002-07-03 22:43:50
Subject: Re: Reclaiminig LTO Tapes
From: Michael Benjamin <MBenjamin AT BUNNINGS.COM DOT AU>
Date: Thu, 4 Jul 2002 10:41:51 +0800
This is correct, 2 drives is not going to cut it, we had similar problems
with a 3575 library with only 2 drives
that used to do our primary backups. The drives are tied up with
reclamations all day long and eventually you
start falling behind and you are not able to migrate data offsite fast
enough, eventually you will run out of incoming
scratch as the library will not be able to recall any vault retrieves, all
in all, a bad situation.

We now operate 5 drives in our 3584 and this is acceptable, we can lose one
drive and still be operating effectively.
Multiple reclamations run on 4 drives at a time when the system is in it's
slack time and gets space reclamation out of
the way very swiftly.

> -----Original Message-----
> From: Tab Trepagnier [SMTP:Tab.Trepagnier AT LAITRAM DOT COM]
> Sent: Thursday, July 04, 2002 6:15 AM
> To:   ADSM-L AT VM.MARIST DOT EDU
> Subject:      Re: Reclaiminig LTO Tapes
>
> Gilbert,
>
> Is there a particular reason you have such a large library with just two
> drives?  I have a 3583 with four drives.  I did that to prevent the very
> problem you're reporting.
>
> Assuming it hosts a primary storage pool, you will need two drives for
> reclamation unless you use a FILE devclass disk pool as a reclaim pool.
> Then you can turn one two-drive process into two one-drive processes with
> a buffer in between them.
>
> If you also might be doing reclamation of your copypool(s) - a situation I
> sometimes see on my system - you will need a third drive.
>
> A fourth drive reserves one drive for "outgoing" data to clients.  That is
> why I put four drives in all four of my tape libraries.
>
> My 3583 connected HV Diff SCSI gives a sustained 12 MB/s per drive.  That
> works out to about 43 GB/hour minus "bubbles" from when the tape is being
> repositioned.
>
> Tab Trepagnier
> TSM Administrator
> Laitram Corporation
>
>
>
>
>
>
> Guillaume Gilbert <guillaume.gilbert AT DESJARDINS DOT COM>
> Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
> 07/03/2002 08:40 AM
> Please respond to "ADSM: Dist Stor Manager"
>
>
>         To:     ADSM-L AT VM.MARIST DOT EDU
>         cc:
>         Subject:        Reclaiminig LTO Tapes
>
>
> Hey there
>
> Maybe its because I'm used to using STK 9840 tapes but yesterday I saw an
> LTO tape at 25 % utilisation take almost 4 hours to reclaim, which to me
> is awful. How am I
> supposed to reclaim my tapes with that kind of performance?. The drives I
> use are IBM Ultriums in a 3584 library. With only 2 drives it makes it
> hard for users to do
> restores...
>
> Are there any options I can change to make this go a bit faster. I know
> the start/stop on LTO's isn't good.
>
> Thanks for the help.
>
> Guillaume Gilbert
> CGI Canada

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