From: Dave Chinner <david@fromorbit.com>
To: David Fuller <dfuller@epoch.com>
Cc: xfs@oss.sgi.com
Subject: Re: Fragmentation Issue We Are Having
Date: Thu, 12 Apr 2012 12:16:26 +1000 [thread overview]
Message-ID: <20120412021626.GX18323@dastard> (raw)
In-Reply-To: <CADrkzimg891ZBGK7-UzhGeey16KwH-ZXpEqFr=O3KwD3qA9LwQ@mail.gmail.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
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next prev parent reply other threads:[~2012-04-12 2:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-12 1:04 Fragmentation Issue We Are Having David Fuller
2012-04-12 2:16 ` Dave Chinner [this message]
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
-- strict thread matches above, loose matches on Subject: below --
2012-04-19 19:54 Richard Scobie
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