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Re: Pre-production questions

To: Joshua Baker-LePain <jlb17@xxxxxxxx>
Subject: Re: Pre-production questions
From: "Martin K. Petersen" <mkp@xxxxxxxxxxxxx>
Date: 20 Mar 2001 08:28:15 -0500
Cc: Linux xfs mailing list <linux-xfs@xxxxxxxxxxx>
In-reply-to: <Pine.LNX.4.30.0103192249060.25325-100000@xxxxxxxxxxxxxxxxxx>
Organization: Linuxcare, Inc.
References: <Pine.LNX.4.30.0103192249060.25325-100000@xxxxxxxxxxxxxxxxxx>
Sender: owner-linux-xfs@xxxxxxxxxxx
User-agent: Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.1 (Canyonlands)
>>>>> "Joshua" == Joshua Baker-LePain <jlb17@xxxxxxxx> writes:

Joshua> My RAID is an IDE-SCSI system -- IDE disks, looks like SCSI to
Joshua> the host.  It has 8 80GB drives in RAID 5, for about 560GB of
Joshua> usable space.  I'd like it to be just one partition.  My
Joshua> question is, are there any special parameters I should pass to
Joshua> mkfs for such a big (well, for me at least) partition?  What
Joshua> about to tailor it to the hardware RAID?

Well.  You could try and hint to the allocator how your RAID device is
set up.  Try and look up which chunk size it uses.  You can pass that
information on to mkfs using the sunit and swidth options.  See the
mkfs.xfs man page for details.

Please note that for a RAID5, choosing the right chunk size for the
workload the crucial for performance.  If you set it too high, you end
up doing a lot of I/O on every write.  If you set it too low, your
sustained I/O performance may suffer.

It all depends on your workload and the RAID array in question (How
much cache it has, etc.)  I recommend you experiment a bit.

Martin K. Petersen, Principal Linux Consultant, Linuxcare, Inc.
mkp@xxxxxxxxxxxxx, http://www.linuxcare.com/
SGI XFS for Linux Developer, http://oss.sgi.com/projects/xfs/

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