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Re: poor io performance with xfs+raid5

To: Steve Lord <lord@xxxxxxx>
Subject: Re: poor io performance with xfs+raid5
From: Mike Eldridge <diz@xxxxxxxxx>
Date: Thu, 25 Apr 2002 14:34:25 -0500
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <1019761870.8309.86.camel@xxxxxxxxxxxxxxxxxxxx>; from lord@xxxxxxx on Thu, Apr 25, 2002 at 02:11:10PM -0500
References: <20020425135652.I16048@xxxxxxxxxxxxxxxx> <1019761870.8309.86.camel@xxxxxxxxxxxxxxxxxxxx>
Sender: owner-linux-xfs@xxxxxxxxxxx
User-agent: Mutt/1.2.5i
On Thu, Apr 25, 2002 at 02:11:10PM -0500, Steve Lord wrote:
> The code which fixes this is stuck in my todo pile in an almost working
> state, but almost working includes a tendency to occasionally do a log 
> write into a random spot and occasionally refuse to mount a filesystem.

ack =(

> we really should remove the growfs info about the log, it has never
> been implemented - we would like to be able to do it too sometimes.
> A bigger log will not help you the fundamental problem here is unaligned
> writes to the log, it causes raid5 to flush its cache, this is the
> performance killer.

aye, i spent quite a while trying to figure out why i couldn't move the
log.  there are several erroneous references to a non-existant -x
switch.  i would definitely recommend removing the growfs info about the
log.

> How recent is your kernel? There are changes recently (last month)
> which reduce kupdated load in xfs dramatically.

vanilla linux-2.4.18 + xfs-1.1

i will gladly try one of the linux-2.4.19pre's if it will help.

-mike

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