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Re: poor io performance with xfs+raid5

To: Austin Gonyou <austin@xxxxxxxxxxxxxxx>
Subject: Re: poor io performance with xfs+raid5
From: Mike Eldridge <diz@xxxxxxxxx>
Date: Thu, 25 Apr 2002 16:08:52 -0500
Cc: Steve Lord <lord@xxxxxxx>, linux-xfs@xxxxxxxxxxx
In-reply-to: <1019767523.23991.2.camel@UberGeek>; from austin@coremetrics.com on Thu, Apr 25, 2002 at 03:45:23PM -0500
References: <20020425154135.B14120@ornery.cafes.net> <1019767523.23991.2.camel@UberGeek>
Sender: owner-linux-xfs@xxxxxxxxxxx
User-agent: Mutt/1.2.5i
i feel like a broken record.  :)

it's an escalade 7850 ata raid card.

-mike

On Thu, Apr 25, 2002 at 03:45:23PM -0500, Austin Gonyou wrote:
> What card is it, BTW?
> 
> 
> On Thu, 2002-04-25 at 15:41, Mike Eldridge wrote:
> > On Thu, Apr 25, 2002 at 03:19:05PM -0500, Steve Lord wrote:
> > > Well, Duh! I should have seen that first time around, I get into the
> > > habit of reading my email too fast!
> > > 
> > > We may be able to fix some things, if we can remake the filesystem.
> > > First you need to know the stripe unit of your raid - we can feed
> > > this into XFS to make it do stripe aligned allocations. This has
> > > to be done by hand on linux. Take a look at the mkfs.xfs man page
> > > and the section on sunit and swidth options. Probably bump your log
> > size
> > > up from the default somewhat, not sure how it ended up as 1839
> > > that is scary.
> > 
> > RAID5 on this card offers only a 64K stripe size.  however, i will be
> > recreating the array as RAID1 or RAID10, which offers stripe sizes from
> > 64K to 1MB.  i'm not sure which is the best way to go.  i think that the
> > best thing to do, considering additonal space requirements might be
> > neccessary, is to go with multiple RAID1 arrays and let LVM do the
> > striping.  any caveats here?
> > 
> > this particular box is a mail server and it handles a lot of i/o with
> > pretty small files (< 64K).  i want to optimize for performance.
> > unfortunately, this is also my *first* foray into xfs/lvm/raid, so i
> > want to make sure i have as much information as possible before i carve
> > it all in stone.
> > 
> > i need to go read some more about LVM...
> > 
> > as for the log, yeah, just over 7MB, i have no idea either.  info i have
> > read suggests a 32MB log, but i'd like to use something bigger, perhaps
> > 128MB.  any caveats to using a log of this size?
> > 
> > > You still have not said which kernel version you are running beyond
> > 2.4,
> > > unless I speed read over that too.
> > 
> > i did in a previous email.  :)
> > 
> > it's vanilla 2.4.18 with the xfs-1.1 release patches applied.
> > 
> > -mike
> > 
> > ------------------------------------------------------------------------
> > --
> >    /~\  the ascii                       all that is gold does not
> > glitter
> >    \ /  ribbon campaign                 not all those who wander are
> > lost
> >     X   against html                          -- jrr tolkien
> >    / \  email!
> > 
> >           radiusd+mysql: http://www.cafes.net/~diz/kiss-radiusd
> > 
> > ------------------------------------------------------------------------
> > --
> -- 
> Austin Gonyou
> Systems Architect, CCNA
> Coremetrics, Inc.
> Phone: 512-698-7250
> email: austin@xxxxxxxxxxxxxxx
> 
> "It is the part of a good shepherd to shear his flock, not to skin it."
> Latin Proverb




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   \ /  ribbon campaign                 not all those who wander are lost
    X   against html                          -- jrr tolkien
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