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Re: blocksize question

To: Mike Young <myoung@xxxxxxxxxxxxxxxxxxx>
Subject: Re: blocksize question
From: Eyal Lebedinsky <eyal@xxxxxxxxxxxxxx>
Date: Thu, 01 Jan 2004 11:46:41 +1100
Cc: "'linux-xfs list'" <linux-xfs@xxxxxxxxxxx>
Organization: Eyal at Home
References: <200312311558.HAA24969@amber.he.net>
Sender: linux-xfs-bounce@xxxxxxxxxxx
Mike Young wrote:
> Hi Eyal,
> I'm currently doing some performance testing with 3Ware and some other RAID
> options on SuSE 9.0 and using XFS.  What kind of performance are you seeing?
> And what tests are you using?

We have a 7500-12, The raid5 is 8 disks + hot spare (XFS mounted
on /backup). We attempted to add a raid0 with two disks but this
seems to be too much load. This two disk raid0 was software raid
but we kept getting io errors
        {DriveReady SeekComplere Error}

The test is simply reading or writing (dd) a large file. For example:
        10GB /dev/zero   -> /backup     3m57 (43 MB/s)
        10GB /backup     -> /dev/null   7m20 (23 MB/s)
We do each 'dd' twice and take the second copy as the result. The
machine is otherwise idle.

This copying is a good measure for us since this machine is an online
backup service and it will mostly have large files copied to it and
from it.

Each disk alone on an IDE cable does about 55MB/s (hdparm, not real

Here are the results for the raid0 on the 3ware (/dev/sdb, ext2
on /ssaback):
        10GB /dev/zero   -> /ssaback    3m52 (44 MB/s)
        10GB /ssaback    -> /dev/null   2m42 (63 MB/s)

BTW, the XFS uses an internal log. I wonder if we should move to
an external log?

The machine is a dual AMD MP 2100+ with 1GB RAM.

Eyal Lebedinsky (eyal@xxxxxxxxxxxxxx) <http://samba.org/eyal/>

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