ADSM-L

Re: LTO restore performance - seek problem?

2001-05-04 13:03:04
Subject: Re: LTO restore performance - seek problem?
From: Bern Ruelas <bern AT CADENCE DOT COM>
Date: Fri, 4 May 2001 09:48:48 -0700
John,

This problem is very interesting to me as we are thinking of throwing away our
17 ATL libraries running Legato's NetWorker 6.0.1 in favor of 2 LTO 3584's running
Tivoli Storage Manager (we will actually use a Sun E420). I thought colocation
was suppose to speed up recoveries, it sounds as if it's not working as advertized....
-Bern
At 02:47 PM 5/4/2001 +0200, Karsten Hüttmann wrote:
At 02:47 PM 5/4/2001 +0200, Karsten Hüttmann wrote:
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Hi!
Your problem sounds familiar to me.
We've similar problems running HSM (or now: Tivoli Space Manager) with
a LTO 3583. (Ok, it is not the best way to use a LTO Library with
HSM, but that was not my decision). For a recall of 2 GBs we need half a
day.
But: a normal restore of a client is as fast as we expected.

John Schneider wrote:

> Greetings,
>     I have seen many posts on adsm.org about LTO, but none that
> addresses the problem I am seeing.  Backup speed seems to be fine, at
> least as far as I can tell.  But when I do a restore, I see a strange
> behavior.  The restore seems to happen in bursts, where the restore
> pulls back files lickety-split for a awhile, then stops for 15-20
> minutes, then continues.  I think that the wait is the seek from one
> spot on the tape to another.  We have two tape drives in the IBM 3583
> library, and the problem seems to be happening on both of them.  We
> upgraded to the 0CE1 version of the LTO microcode, but it has not
> improved things that I can tell.
>     We restored 1.5 GB from our RS/6000 TSM server to a NT client, and
> it took 47762 seconds, or 13 hours.  All the data was on one tape, so it
> is not a colocation problem.  How long should it take an LTO drive to
> seek?  I have done these sort of restores on DLT, and it can usually get
> from any place to any place on a tape within a few minutes.  I expected
> LTO to be at least as good.  A 13 hour restore is completely
> unacceptable.
>     Any input or things to try would be appreciated.  By the way, the
> TSM server is an RS/6000 F50 running AIX 4.3.3 ML4, with TSM 4.1.2.  It
> is running atape 6.0.4, and atldd 4.1.5.0, which are both the latest, I
> believe.  The NT client was TSM 4.1.2.  Both are on the same switch on a
> 100MB Ethernet network, so I don't think the network is related in any
> way.
>
> TIA,
> John Schneider
>
> ***********************************************************************
> * John D. Schneider   Email: jdschn AT attglobal DOT net * Phone: 636-492-0247
> * Lowery Systems, Inc.
> * 1329 Horan                  Disclaimer: Opinions expressed here are
> * Fenton, MO 63026                   mine and mine alone.
> ***********************************************************************

--
Mit freundlichen Grüssen / with regards
Karsten Hüttmann

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