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From: David Fuller <dfuller@epoch.com>
To: xfs@oss.sgi.com
Subject: Fragmentation Issue We Are Having
Date: Wed, 11 Apr 2012 18:04:25 -0700	[thread overview]
Message-ID: <CADrkzimg891ZBGK7-UzhGeey16KwH-ZXpEqFr=O3KwD3qA9LwQ@mail.gmail.com> (raw)


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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.  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


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%



Regards,
David Fuller

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             reply	other threads:[~2012-04-12  1:04 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-12  1:04 David Fuller [this message]
2012-04-12  2:16 ` Fragmentation Issue We Are Having Dave Chinner
2012-04-12  2:55   ` David Fuller
2012-04-12  4:24     ` Eric Sandeen
2012-04-12  7:57 ` Brian Candler
2012-04-13  0:09   ` David Fuller
2012-04-13  7:19     ` Brian Candler
2012-04-13  7:56       ` Dave Chinner
2012-04-13  8:17         ` Brian Candler
2012-04-17  0:26           ` Dave Chinner
2012-04-17  8:58             ` Brian Candler
2012-04-18  1:36               ` Dave Chinner
2012-04-18  9:00                 ` Brian Candler
2012-04-19 23:12                   ` Dave Chinner
2012-04-19 19:54 Richard Scobie

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