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    SubjectRe: xfs: very slow after mount, very slow at umount
    On Wed, Jan 26, 2011 at 10:49:03PM -0500, Mark Lord wrote:
    > On 11-01-26 10:30 PM, Dave Chinner wrote:
    > > [Please cc xfs@oss.sgi.com on XFS bug reports. Added.]
    > >
    > > On Wed, Jan 26, 2011 at 08:22:25PM -0500, Mark Lord wrote:
    > >> Alex / Christoph,
    > >>
    > >> My mythtv box here uses XFS on a 2TB drive for storing recordings and videos.
    > >> It is behaving rather strangely though, and has gotten worse recently.
    > >> Here is what I see happening:
    > >>
    > >> The drive mounts fine at boot, but the very first attempt to write a new file
    > >> to the filesystem suffers from a very very long pause, 30-60 seconds, during which
    > >> time the disk activity light is fully "on".
    > >
    > > Please post the output of xfs_info <mtpt> so we can see what you
    > > filesystem configuration is.
    >
    > /dev/sdb1 on /var/lib/mythtv type xfs
    > (rw,noatime,allocsize=64M,logbufs=8,largeio)
    >
    > [~] xfs_info /var/lib/mythtv
    > meta-data=/dev/sdb1 isize=256 agcount=7453, agsize=65536 blks
    > = sectsz=512 attr=2
    > data = bsize=4096 blocks=488378638, imaxpct=5
    > = sunit=0 swidth=0 blks
    > naming =version 2 bsize=4096 ascii-ci=0
    > log =internal bsize=4096 blocks=32768, version=2
    > = sectsz=512 sunit=0 blks, lazy-count=0
    > realtime =none extsz=4096 blocks=0, rtextents=0

    7453 AGs means that the first write coud cause up to ~7500 disk
    reads to occur as the AGF headers are read in to find where the
    best free space extent for allocation lies.

    That'll be your problem.

    Cheers,

    Dave.
    --
    Dave Chinner
    david@fromorbit.com


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