ADSM-L

Re: diskpool performance

2002-07-26 15:53:28
Subject: Re: diskpool performance
From: "Kelly J. Lipp" <lipp AT STORSOL DOT COM>
Date: Fri, 26 Jul 2002 13:52:22 -0700
Our experience with disk pools on RAID5 volumes has indicated that slow
performance is the norm rather than the exception.  This is especially true
when more than one operation was running at a time, i.e., more than one
client session, more than one migration or backup stg operation.  We have
taken to putting disk pool volumes on JBOD disks rather than on RAID5 disks.
Dramatic performance improvements when we made this change.

So, that might indicate why your disk pools are slow.

I'll also concur with Paul: tape is not necessarily slower than disk.  In
fact, our experience, again, has shown that backup directly to tape is as
fast as backup to disk.  That said, if you have gazillions (technical term)
of small files, this might not be the case.  But I'm thinking client to disk
won't be all that fast either.

We are routinely seeing 35-40 GB/hour data transfer rates to tape (all
varieties: LTO, SDLT, AIT3) either from disk to tape operations or client
operations.

Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs, CO 80949
lipp AT storsol DOT com or kelly.lipp AT storserver DOT com
www.storsol.com or www.storserver.com
(719)531-5926
Fax: (240)539-7175


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