On Fri, Nov 09, 2007 at 08:40:15PM +0200, Enache Adrian wrote:
> On Fri, Nov 09, 2007 at 11:03:31AM +0100, Otto Moerbeek wrote:
> > So your problem seems to be that rsync -S is inefficient to the point
> > where it is not useable. I do not use rsync a lot, so I do not know
> > if there's a solution to that problem. It does seem strange that a
> > feature to solve a problem actually make the problem worse.
>
> Anything is inefficient in that case.
>
> Just create a huge dummy file:
>
> $ dd if=/dev/null seek=1m bs=1m of=file
>
> Then copy it (with cp, or any sparse-file aware program) to another
> filesystem. Watch how much time and power it takes to copy nothing
> from one place to another.
>
> Any way to obtain a 'map' of the file that tell you exactly where the
> written sectors are would make for a BIG improvement.
>
> You can't do that on OpenBSD without raw low-level fs hacks and
> reinventing half of dump(8) and fsck(8).
>
> Adi
Your example just shows copying big files takes long. The point being,
if the file was not sparse, it would take at least the same time.
Blaming sparseness for the long cp time is not "fair".
-Otto
