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

To: Jani Jaakkola <jjaakkol@xxxxxxxxxxxxxx>
Subject: Re: nfs/local performance with software raid5 and xfs and SMP
From: Steve Lord <lord@xxxxxxx>
Date: Mon, 23 Jul 2001 09:43:22 -0500
Cc: "linux-xfs@xxxxxxxxxxx" <linux-xfs@xxxxxxxxxxx>
In-reply-to: Message from Jani Jaakkola <jjaakkol@cs.helsinki.fi> of "Mon, 23 Jul 2001 17:34:14 +0300." <Pine.LNX.4.33.0107231617490.4170-100000@hallikari.cs.Helsinki.FI>
Sender: owner-linux-xfs@xxxxxxxxxxx
> On Mon, 23 Jul 2001, Jani Jaakkola wrote:
> 
> > Hmm, I'll guess I have to get my hands on some other benchmark software
> > than bonnie and try it with ext2, xfs+internal log and xfs+external log.
> 
> OK, it seems that create/delete performance on linux XFS with sw RAID is
> still bad with current cvs kernel (not terrible anymore, but bad enough
> that I would not put xfs with sw RAID to production use). I downloaded
> bonnie++ and did some tests
> 

> 
> So the RAID array is 5 times faster in pure write IO, but xfs with
> internal log kills create/delete performance with IO stalls. With external
> log the create/delete performance is again acceptable:
> 
.....
> 
> So the sw RAID internal log performance is not fixed yet :(

No performance is not 'fixed' but it is way better than it was in the
earlier kernels, we had a scenario where it would just stop dead in
its tracks and not make any forward progress.

It is more complex to setup with the external log, but it looks like a
pretty viable solution - see Tru Huynh's numbers with a raid1 journal,
this config still has everything protected and is getting good numbers.

Steve

> 
> - Jani




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