[mythtv-users] Does JFS filesystem need defragment?

[James Oltman]

On Nov 10, 2007 10:51 AM, George Mari <george_mythusers at mari1938.org> wrote:

> Ismo Tanskanen wrote:
> > I use JFS file system for myth recordings, because it's ability to
> > delete files quickly.
> >
> > Now I'm wondering, if it needs defragment time to time? Does it? Is
> > there any utility to do that?
> >
> > Or is there better filesystem for myth recordings?
> >
> >
>
> I use JFS for my recordings as well.  I've done some research and was
> not able to find any defragging utility that would work with JFS.
>
> I've also not found any evidence that JFS needs to be defragmented.
>
> I run FC6, so I grabbed the e2fsprogs package which includes the
> filefrag utility.  You can point the filefrag utility at your recordings
> directory and it will tell you how many extents (fragments) each file is
> stored in.  My filesystem is pretty full, so most of my recordings are
> fragmented in 2 to 12 fragments.  With this level of fragmentation I
> don't notice any performance issues.
>
> If you really want to defragment your JFS filesystem, you could move all
> your files off the filesystem, delete them from the original location,
> and then copy them back.
>

I also use JFS and last week I had a big time scare.  I'm running 5x500 GB
SATA drives in a mdadm RAID5 On MythDora 4.0.  I was having trouble with
changing ownership of all the files/folders on the drive.  So I stopped the
mythbackend service and umounted the drive.  I went to remount it, and it
wouldn't mount.  I was TERRIFIED.  I was getting these cryptic error
messges.  After some research, I decided to run a file check on the drive.
So I downloaded the jfs-utils RPM and ran that.  It found some errors and
fixed them.  I only have about 200GBs left on that RAID array.  I'm
considering adding more drives.  Should I not be using JFS since
fragmentation might have caused this issue?  I know XFS has issues with 4K
stacks which is what Mythdora uses IIRC.  Any ideas?

Jim
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