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@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
