Speed problem

Wayne Davison wayned at users.sourceforge.net
Wed Nov 13 07:35:59 EST 2002

On Tue, Nov 12, 2002 at 11:30:28PM +0100, uwp at dicke-aersche.de wrote:
> And why it tries to get 100% CPU even though there's nothing to do ?

What do you mean "nothing to do"?  Rsync is creating the new version of
a changed file which is done both by transferring data over the network
and by copying matching data from the existing version of the file.
Just because nothing is being transferred over the link doesn't mean
nothing is going on.  Or is there some other problem that I missed in
this discussion?

> Ok, that I never tried because I thought the --partial option should
> have been the fastest method because lots of data is still on the other
> side if an error has occured before.

The --partial option ensures that if we transferred a lot of data to
build a file but didn't finish it, that this data is not just thrown
away.  However, if we started with an already-existing version of a file
that was mostly the same as the new version, it is possible that when
rsync is interrupted the current partial file actually contains less
matching data in it than the already-existing version, and thus
retaining this partial file actually makes the next transfer less
efficient.  Because of this I only use the --partial option if I'm
sending really big *new* files, not updating really big existing files.


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