rsync (or rsync-like tool) provides local metadata cache ?

[Jason Usher]

Hi,

--- On Fri, 9/30/11, Johannes Totz <jtotz at imperial.ac.uk> wrote:

> > Let's say I have a slow, or high latency (or both)
> link between two
> > hosts, and transferring data is expensive.
> > 
> > Is it possible with rsync (or any other tool like
> rsync) to maintain
> > a local metadata cache, such that I can rsync without
> transferring
> > data to and from the hosts about what files are
> already in place ?
> > 
> > That is, I already "know" what is out there and don't
> need to check
> > anything - I can just use the state information on the
> sending end to
> > send only the data required, and don't need to
> traverse the remote
> > filesystem for sizes/datestamps/hashes/etc.
> > 
> > Does this exist ?
> 
> Check out the checksum database patches. Maybe these could
> help in your
> case...


Thank you.  Do these patches only apply if I am comparing based on checksums ?  What if I am only comparing based on time/date, or size - is there a strategy for saving time and bandwidth in that case ?

Thanks.