[mythtv-users] Fragmentation On Recording Disk?
mythtv at rodsbooks.com
Wed Apr 4 18:40:48 UTC 2007
On Wednesday 04 April 2007 14:24, jason maxwell wrote:
> On 4/4/07, Matt Doran <matt.doran at papercut.biz> wrote:
> > Tim Phipps wrote:
> > Are disks formatted with
> > ext3 showing the same fragmentation factor ? And does one know the growth
> > rate of this factor ? (what are the relevant variables : disk size ?
> > technology ? file system ?)
> I thought that with ext2/3 fragmentation was kept in check by regular
No -- or at least, not as far as I know. To the best of my knowledge, fsck
does nothing about fragmented files. My understanding is that ext2/3 doesn't
fragment much because of its design, or rather the design of its Linux
drivers, which try to place files where they can grow, rather than just
cramming them in one after another, as DOS did.
> I may be wrong, but I've been using linux for a decade and
> have never noticed any performace symptoms that would make me think I
> needed a defrag.
Most Linux systems create files that are far smaller than the multi-gigabyte
files that are common with MythTV. If a 5GB recording of a TV show is
fragmented into 500 parts, that's about 10MB per fragment, which is larger
than most files on most non-MythTV Linux systems.
I don't know the exact algorithms used by the different filesystems for where
to place new files. No doubt those would affect fragmentation, and it might
be useful to change, or at least tune, these algorithms for filesystems that
store particularly large files. I've not looked into this matter, though; I
don't know if there are any tuning parameters for ext3fs, XFS, or any other
filesystem that might be useful for MythTV users.
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