Behavior of --checksum, suggestion

Moshe Jacobson moshe at
Tue Jun 7 21:44:25 GMT 2005

Thanks for the prompt reply, Wayne.

I just did a test and found that --partial will prevent rsync from
transferring the entire file again when the mtimes vary but the sizes
are the same.  I suppose this is sufficient, but how does it determine
that the files are the same if it's not doing a checksum or
transferring the entire file?


whole file again if the size is the same and the mtime is different

On Tue, 7 Jun 2005, Wayne Davison wrote:

> On Tue, Jun 07, 2005 at 04:46:43PM -0400, Moshe Jacobson wrote:
>> Is this something that would be hard to implement?
> Yes, it would be rather awkward in the current protocol.  The way things
> currently work, the receiving side needs to have all relevant info
> already available in order to decide what files to send.  One possible
> solution would be to add an extra "phase" prior to the file-transfer
> phase (before the receiving side forks) where the receiver makes a pass
> through the files and requests checksums for files that might need to be
> transferred, and then proceeds on to the normal checksum-sending phase
> (after forking) but with an optimization that allows it to avoid calling
> stat() on all the files all over again (it would flag changed files,
> required dirs, etc. during the earlier checksum phase).
> So, that would be quite a big change, which probably means that it won't
> happen -- at least, not in the current rsync (hopefully a future,
> improved-protocol rsync will be more flexible in this regard, and it
> would sure be nice to get around to working on it again before too
> long).
> ..wayne..

Moshe Jacobson -- -- AIM: Jehsom
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