From: Dave Chinner <david@fromorbit.com>
To: Tom Crane <T.Crane@rhul.ac.uk>
Cc: Christoph Hellwig <hch@infradead.org>,
Eric Sandeen <sandeen@sandeen.net>,
xfs@oss.sgi.com
Subject: Re: xfs_repair segfaults with ag_stride option
Date: Wed, 8 Feb 2012 20:00:41 +1100 [thread overview]
Message-ID: <20120208090041.GJ20305@dastard> (raw)
In-Reply-To: <4F316236.7050607@rhul.ac.uk>
On Tue, Feb 07, 2012 at 05:41:10PM +0000, Tom Crane wrote:
> Eric Sandeen wrote:
> >On 2/6/12 5:19 AM, Tom Crane wrote:
> >>Eric Sandeen wrote:
> >
> >...
> >
> >>>Newer tools are fine to use on older filesystems, there should be no
> >>Good!
> >>
> >>>issue there.
> >>>
> >>>running fsr can cause an awful lot of IO, and a lot of file reorganization.
> >>>(meaning, they will get moved to new locations on disk, etc).
> >>>
> >>>How bad is it, really? How did you arrive at the 40% number? Unless
> >>xfs_db -c frag -r <block device>
> >
> >which does:
> >
> > answer = (double)(extcount_actual - extcount_ideal) * 100.0 /
> > (double)extcount_actual;
> >
> >If you work it out, if every file was split into only 2 extents, you'd have
> >"50%" - and really, that's not bad. 40% is even less bad.
>
> Here is a list of some of the more fragmented files, produced using,
> xfs_db -r /dev/mapper/vg0-lvol0 -c "frag -v" | head -1000000 | sort
> -k4,4 -g | tail -100
>
> >inode 1323681 actual 12496 ideal 2
> >inode 1324463 actual 12633 ideal 2
.....
> >inode 1320625 actual 20579 ideal 2
> >inode 1335016 actual 22701 ideal 2
> >inode 753185 actual 33483 ideal 2
> >inode 64515 actual 37764 ideal 2
> >inode 76068 actual 41394 ideal 2
> >inode 76069 actual 65898 ideal 2
Ok, so that looks like you have a fragmentation problem here. What
is the workload that is generating these files?
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2012-02-08 9:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 13:36 xfs_repair segfaults with ag_stride option Tom Crane
2012-02-02 12:42 ` Christoph Hellwig
2012-02-06 0:50 ` Tom Crane
2012-02-06 5:58 ` Eric Sandeen
2012-02-06 11:19 ` Tom Crane
2012-02-06 13:21 ` Eric Sandeen
2012-02-07 17:41 ` Tom Crane
2012-02-07 18:00 ` Eric Sandeen
2012-02-08 9:00 ` Dave Chinner [this message]
2012-02-06 14:04 ` Christoph Hellwig
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