From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q3C2GWe7178956 for ; Wed, 11 Apr 2012 21:16:32 -0500 Received: from ipmail06.adl2.internode.on.net (ipmail06.adl2.internode.on.net [150.101.137.129]) by cuda.sgi.com with ESMTP id xSjDKVbItGuuiw9S for ; Wed, 11 Apr 2012 19:16:29 -0700 (PDT) Date: Thu, 12 Apr 2012 12:16:26 +1000 From: Dave Chinner Subject: Re: Fragmentation Issue We Are Having Message-ID: <20120412021626.GX18323@dastard> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: David Fuller Cc: xfs@oss.sgi.com On Wed, Apr 11, 2012 at 06:04:25PM -0700, David Fuller wrote: > We seen to be having an issue whereby our database server > gets to 90% or higher fragmentation. When it gets to this point > we would need to remove form production and defrag using the > xfs_fsr tool. Bad assumption. > The server does get a lot of writes and reads. Is > there something we can do to reduce the fragmentation or could > this be a result of hard disk tweaks we use or mount options? > > here is some fo the tweaks we do: > > /bin/echo "512" > /sys/block/sda/queue/read_ahead_kb > /bin/echo "10000" > /sys/block/sda/queue/nr_requests > /bin/echo "512" > /sys/block/sdb/queue/read_ahead_kb > /bin/echo "10000" > /sys/block/sdb/queue/nr_requests > /bin/echo "noop" > /sys/block/sda/queue/scheduler > /bin/echo "noop" > /sys/block/sdb/queue/scheduler They have no effect on filesystem fragmentation. > Adn here are the mount options on one of our servers: > > xfs rw,noikeep,allocsize=256M,logbufs=8,sunit=128,swidth=2304 > > the sunit and swidth vary on each server based on disk drives. > > We do use LVM on the volume where the mysql data is stored > as we need this for snapshotting. Here is an example of a current state: > > xfs_db -c frag -r /dev/mapper/vgmysql-lvmysql > actual 42586, ideal 3134, fragmentation factor 92.64% Read this first: http://xfs.org/index.php/XFS_FAQ#Q:_The_xfs_db_.22frag.22_command_says_I.27m_over_50.25.__Is_that_bad.3F Then decide whether 10 extents per file is really a problem or not. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs