Backup methods

[Jason L Tibbitts III]

Cyrus does have an integrated backup system (see
https://cyrusimap.org/imap/reference/admin/backups.html) which I'm not
sure has been mentioned in this thread.  But you still have to have
enough space to keep the compressed backups on disk in order to move
them to tape or whatever archival storage you're using.  There is
discussion of the storage requirements in the documentation.  I don't
think any of it is particularly unreasonable, but I haven't actually
tried it myself.

Technically I don't think you need a separate machine (though that's
simpler); it may just be possible to have a second cyrus server
listening on different ports to act as the replication target.  I
probably wouldn't do it that way anyway; old hardware with some cheap
disk would suffice to stage the backups until they're sent to tape or
wherever.

As for it all being marked "experimental", I'm sure that if bugs were
found (and reported), they would be fixed.  It probably just needs more
testing and back and forth with the devs to flesh out the documentation
and add any missing functionality.

 - J<