Synchronised mail-directories advise

[Paul Dekkers]

Hi,

I'm running Cyrus IMAPd for a about 3 years now, and I'm really happy
with it. I'm still running v1.6.24 without any problems. (I'm not aware
of any security issues, if there are any, or other disadvantages of
running this version I'd really like to know. I haven't looked cyrus for
some time since it suits my needs and runs fine.)

One thing I want to implement is redundant mail storage. The way I think
about doing this, is running one master box, that runs unison (good
bi-directional synchronisation, can be compared to rsync) either after
the user modified some data, or at a specified interval (I think that's
the best option). I want to synchronise it then to a box in the same
subnet, so it can take over it's IP-address if the first one fails.

The only thing that does not work with this unison-trick I think is the
cyrus.* files: if the other files are changed on one of the boxes, these
files are not synchronisable. I think the best option is then run a
reconstruct for every (changed) mailbox after the unison job.

Can anyone advise me on this issue? Is this a good way of doing things,
or will I face some problems I don't see yet? (Is it wise to upgrade?)
This would really work with Maildir-mailboxes, since there are no
cache's and index-files. I'd like to keep cyrus however, because of the
shared mailboxes e.g.

Thank you in advance,
Paul