rsync and cyrusimap.2.4.x

[Bron Gondwana]

On Tue, Nov 23, 2010 at 05:13:51PM +0100, Martin Pracht wrote:
> 
> Hello,
> 
> with 2.3.X we were happy by having
> a standby-system for our mail server,
> keeping the data up to date by a
> periodical rsync from the working system.
> We did an upgrade to 2.4.X on the
> standby-system. With 2.4.X "reconstruct" seems
> to change the modification-time of all mail-files,
> on next invocation that triggers rsync to transfer
> all files, which causes too much load and
> takes too much time.

Eep - why would you run a different version of Cyrus
on your replica than your master.

Also: the cyrus.index file is a new format on 2.4.x
and will be upgraded on the fly.  Unless you don't
care about you users' flag updates at all, you'll
wind up have to re-create it all the time from 
rsynced copies on the master.  It's an all around
bad idea!
 
> Is the only solution for this the use
> of replication instead of rsync?

That's certainly a good solution - but if you use
2.4.x on both ends, the modifictation times should
also be identical (they're based on the internaldate)

If you don't rsync the cyrus.index files as well you're
probably pretty screwed when you do a reconstruct, because
it's going to have to guess what the internaldate should be.

Bron.