Bug 515191

If /home is 96% full the file may be highly fragmented.

point filefrag [-v] at the file you're testing, we can see how fragmented it is.

-Eric

(In reply to comment #2)
> point filefrag [-v] at the file you're testing, we can see how fragmented it
> is.

Whoa, the file seems to be fragmented badly:

[max@truth ~]$ sudo filefrag ~/Videos/Home.2009.Bluray.720p.AC3.x264-CHD.mkv
/home/max/Videos/Home.2009.Bluray.720p.AC3.x264-CHD.mkv: 449868 extents found, perfection would be 41 extents

I tried reading a non-fragmented file:

[max@truth ~]$ sudo filefrag ~/Videos/TOM.AVI 
/home/max/Videos/TOM.AVI: 7 extents found

[max@truth ~]$ dd if=~/Videos/TOM.AVI of=/dev/null bs=1M count=728
690+1 records in
690+1 records out
723529728 bytes (724 MB) copied, 11.0531 s, 65.5 MB/s

So, the issue seems to be high fragmentation.

Thank you guys.

Max

p.s.: I probably need to make eMule preallocate the whole file! ;)

Yup I was going to ask whether it was a torrent ;)

Some torrent clients will do nice preallocation on ext4 or xfs, which support fast preallocation; something you might consider.

-Eric

(In reply to comment #4)
> Yup I was going to ask whether it was a torrent ;)

Correction: I use aMule, not eMule. I use Transmission too, but BitTorrent being the hottest topic nowadays I'd like to keep under radars sometimes by using eDonkey network. And I love the integrated search.

offtopic: Having mentioned BitTorrent, I think there is at least one good idea how to make seeders anonymous (which solves legal issues in some states), so if anyone cares here is a link http://max0x7ba.blogspot.com/2009/07/how-to-build-anonymous-peer-to-peer.html I hope one smart hacker integrates something like that in BitTorrent transfer protocol.
 
> Some torrent clients will do nice preallocation on ext4 or xfs, which support
> fast preallocation; something you might consider.

I now definitely will!

By any chance, do you know of a tool that generates some sort of a filesystem fragmentation report (apart from manual `find <folder> -type f -exec filefrag {} \; | <some-formatter-script>)`?

And, while we are at it, is there any recommended filesystem (ext3 in my case) defragmenter tool? (I did a quick google search on "ext3 defragment" and there are no hot hits, and the source of all knowledge (Wikipedia) says "... A true defragmentation tool does not exist for ext3..."

Max

(In reply to comment #5)
> (In reply to comment #4)

...

> > Some torrent clients will do nice preallocation on ext4 or xfs, which support
> > fast preallocation; something you might consider.
> 
> I now definitely will!
> 
> By any chance, do you know of a tool that generates some sort of a filesystem
> fragmentation report (apart from manual `find <folder> -type f -exec filefrag
> {} \; | <some-formatter-script>)`?

latest e2fsck with some degree of "-v" gives a total fragmentation info.

git e2fsprogs has an "e2freefrag" tool for freespace

xfs_db can do "frag" and "freesp" to get some idea of file & freespace fragmentation.

> And, while we are at it, is there any recommended filesystem (ext3 in my case)
> defragmenter tool? (I did a quick google search on "ext3 defragment" and there
> are no hot hits, and the source of all knowledge (Wikipedia) says "... A true
> defragmentation tool does not exist for ext3..."

that's true.

ext4 will get e4defrag eventually, a rough cut is in git.
xfs has xfs_fsr, which works.

-Eric