Date: Sun, 29 Jul 2001 15:32:28 -0500 (CDT)
From: Chris Bednar <cjb@AdvancedDataSolutions.com>
To: Seth Mos <knuffie@xs4all.nl>
cc: Linux XFS Mailing List <linux-xfs@oss.sgi.com>
Subject: Re: raid5 resync aborted under heavy XFS use
In-Reply-To: <4.3.2.7.2.20010729202627.0384c340@pop.xs4all.nl>
Message-ID: <Pine.LNX.4.10.10107291519140.11670-100000@linux1.production.mnd.com>
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> there are some slight problems with xfs over software raid5 that have just 
> been fixed in the CVS tree. There were also IO stall problems with this 
> setup when you have a internal log. Basically you also want to make the log 
> an external log which has a large performance boost.
> 
> Search the archive for discussion about this. 1 week ago it was discussed 
> and it has some bencmarks to back it up.

    I've seen them. For some reason, I'm suspicious that this
is a different problem.

    An external log is scary to me;  I can afford lackluster
write performance easier than I can afford:

  ``You know that $16k RAID setup you bought? it's gone to Hell
    because the one disk I was using for the log croaked.''

or:

  ``You know that big RAID system? Well, I moved it from one 
    machine to another, and now it won't work.''

In my opinion, an internal log has to work reasonably well for
XFS to be viable. It's fine, of course, if an external log works
better, and I don't mind doing that on my own systems.

    I'll take a shot at CVS... by the way, is an internal log
also a performance issue on IRIX systems?


----
Chris J. Bednar   <http://optics.tamu.edu/~bednar/>
Director, Distributed Computing Product Group
http://AdvancedDataSolutions.com/