More on file fragmentation, torrents, etc.....

[Tom Mitchell]

On Tue, Apr 27, 2004 at 07:43:40PM -0800, t l wrote:

> I just checked the fragmentation on the files in the second torrent
> (the sources). They are disasterously worse:
> 
> [root at fedora FC2-test3-src-i386]# filefrag *
> FC2-test3-i386-SRPMS-disc1.iso: 23626 extents found, perfection would be 4 extents
> FC2-test3-i386-SRPMS-disc2.iso: 66563 extents found, perfection would be 4 extents
> FC2-test3-i386-SRPMS-disc3.iso: 120911 extents found, perfection would be 4 extents
> FC2-test3-i386-SRPMS-disc4.iso: 112109 extents found, perfection would be 4 extents
> 
> 120,000 extents ?!?!
> 
> No wonder my machine was reduced to less than a crawl.
> 
> Any hints on what I did wrong?

I doubt that you did anything wrong.  One of the things that torrent
does is fragment the way it gets the files all different parts at the
same time from piles of places.  I have 3% of the download on one
collection but have some bits for all the iso images in it.

If it is really slowing you down, you should be able to clean it up by
stopping the torrent making a copy and remove the downloaded file with
all the insane extents, then rename the copied files  back as they
were and then restart torrent.

  Something like:
     mv FC2-test3-i386-SRPMS-disc1.is foo
     cp foo FC2-test3-i386-SRPMS-disc1.iso
     rm foo
  or better yet:
     cp FC2-test3-i386-SRPMS-disc1.is foo
     filefrag FC2-test3-i386-SRPMS-disc1.is foo
     # pick the best and give it the name you and torrent expect.

It might take a couple of copy and move cycles of these big old files
for the filesystem to tidy things up... much will depend on how full
the FS is and what else is going on.

It will be interesting to hear back, I believe filefrag is new in
e2fsprogs-1.35-7.1.  In one copy/rename cycle on an old iso image I
went from 1063 extents to 164 extents.  One more time and I was back
up to 324 extents but the filesystem was not idle.

None of mine are as bad as yours appear to be. How full is your
filesystem?  Making a bit of space by moving things to a different
filesystem then back can help bunches.

As always, double check the MD5SUMS with this sort of tinkering.


-- 
	T o m  M i t c h e l l 
	/dev/null the ultimate in secure storage.