no "defrag" in Linux?

[Henk Postma]

On 7/20/06, Peter Garrett <peter.garrett at optusnet.com.au> wrote:

> $ sudo filefrag ED_1024.avi
> ED_1024.avi: 294 extents found, perfection would be 4 extents
>
> $ time cat ED_1024.avi > /dev/null
>
> real    0m11.178s
> user    0m0.052s
> sys     0m1.056s
>
> $ cp ED_1024.avi ED_1024-new.avi
> $ sudo filefrag ED_1024-new.avi
> ED_1024-new.avi: 103 extents found, perfection would be 4 extents
>
> $ time cat ED_1024-new.avi > /dev/null
>
> real    0m11.470s
> user    0m0.060s
> sys     0m1.156s

as other people have written, there may be other effects at play. In
addition, the file is not really that much less fragmented. 103 when
'perfection' would be 4? I would say that is still heavily fragmented.
Unfortunately, I don't know how to get the fragmentation much lower,
without trial and error. Even going to single user mode did not seem
to make much of a difference.

-- 
http://www.its.caltech.edu/~postma/