From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Clayton Subject: Re: RAID 5 performance issue. Date: Wed, 3 Oct 2007 21:19:10 +0100 Message-ID: <20071003211910.439ded54@alpha.digital-domain.net> References: <20071003105321.06943824@zeus.pccl.info> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Justin Piszcz Cc: Andrew Clayton , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wed, 3 Oct 2007 12:43:24 -0400 (EDT), Justin Piszcz wrote: > Have you checked fragmentation? You know, that never even occurred to me. I've gotten into the mind set that it's generally not a problem under Linux. > xfs_db -c frag -f /dev/md3 > > What does this report? # xfs_db -c frag -f /dev/md0 actual 1828276, ideal 1708782, fragmentation factor 6.54% Good or bad? Seeing as this filesystem will be three years old in December, that doesn't seem overly bad. I'm currently looking to things like http://lwn.net/Articles/249450/ and http://lwn.net/Articles/242559/ for potential help, fortunately it seems I won't have too long to wait. > Justin. Cheers, Andrew