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Re: nfs/local performance with software raid5 and xfs and SMP

To: Tru Huynh <tru@xxxxxxxxxx>, jjaakkol@xxxxxxxxxxxxxx
Subject: Re: nfs/local performance with software raid5 and xfs and SMP
From: Steve Lord <lord@xxxxxxx>
Date: Thu, 19 Jul 2001 13:12:54 -0500
Cc: Steve Lord <lord@xxxxxxx>, "linux-xfs@xxxxxxxxxxx" <linux-xfs@xxxxxxxxxxx>
In-reply-to: Message from Tru Huynh <tru@xxxxxxxxxx> of "Thu, 19 Jul 2001 19:12:05 +0200." <3B5714E5.44966F10@xxxxxxxxxx>
Sender: owner-linux-xfs@xxxxxxxxxxx
> A little update,
> 
> At least, some better news:
> I did *NOT* see the problem (yet!) with the noapic option
> with 2.4.7pre8-SMP


I am informed that there is a fix in the latest kernels in the raid5 code
to fix some stall issues which ext3 hit. So it maybe that the answer here
is to run the latest kernels. I still do not like the fact we do non-stripe
friendly I/O to the log, and want to look into that.

Jani, this may also be the source of your problems, we did experience
an almost complete lockup here with the 1.0.1 rpm kernel. If you get a
chance can you run the latest cvs kernel?

Steve

> 
> Steve Lord wrote:
> > 
> <...>
> 
> > If you choose another partition (non raid5) for the log and make an externa
> l
> > log instead of using an internal log then the issue should go away, we
> > are going to test this here. I suppose a mirrored log would be the best
> > solution here as you could still survive the loss of a drive with the
> > log on it.
> 
> I wish I could do that :) 
> - hda and hdc on a raid 1 array (system disk) + mirrored xfs log 
> - sda..sdh for a 7 disk + 1 hot spare disk for the raid5 array.
> 
> The only issue is space, trying to squeeze a second IDE disk
> on the second IDE controller will not easily be manageable is
> the rack :(
> I do have a spare system disk on the shelf, and quick method to
> restore the system disk but I would not risk putting the xfs log
> on this lone disk.
> 
> What if I cut the 8 disks in 2 parts
> 1st partition of sd[a..d] of 2 GB (enough?) for a raid10 array for the
> log
> 2nd partition of sd[a..g] for the main raid5 array 
> sdh for the hot spare?
> 
> Best regards,
> 
> Tru
> --
> Dr Tru Huynh          | Bioinformatique Structurale
> mailto:tru@xxxxxxxxxx | tel/fax +33 1 45 68 87 37/19
> Institut Pasteur, 25-28 rue du Docteur Roux, 75724 Paris CEDEX 15 France



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