rsync - Nov 2003 - synchronisation in multiple directions.

We want to have the same files on multiple sites, of which one
act as master.  If the file changes on 1 site it should be moved
to the master, and then from the master to the other sites.

That part shouldn't be that hard to do, but what also should
happen is that if a file is deleted or added on one site it
should get removed or added on the sites too.  And afaik, I can't
currently do that with rsync.

The only solution I can come up with is that you keep track in a
file of what files you last got from the master.  And if the
slave now has a file more than it had last time, transfer it to
the server.  If it has a file less remove it on the server.

Do you think this solution will work?  Or are there better ways?


Kurt

On Fri, Nov 14, 2003 at 07:02:47PM +0100, Kurt Roeckx
wrote:
> That part shouldn't be that hard to do, but what also should happen is
> that if a file is deleted or added on one site it should get removed
> or added on the sites too.  And afaik, I can't currently do that with
> rsync.
That's what "unison" is made to do -- it synchronizes changes
between
two systems (at a time), propagating changing in both directions.  Using
it you can either syncronize everyone to a master system, or you can use
a daisy-chain in a circular run of multiple systems (e.g. A syncs with
B, B syncs with C, C syncs with A).  Unison uses the rsync algorithm to
transfer its files, so it's network-efficient like rsync.

Alternately, use a distributed file system, such as AFS or SFS.

..wayne..