mail server replication
Paul.Dekkers at surfnet.nl
Thu May 20 13:21:45 EDT 2004
Gerard Ceraso wrote:
>I have a server setup using Cyrus 2.1 and postfix, with mysql. What I
>would like to have is 2 servers basically the second would be a
>replication of the first server. So I would like to be able to connect
>to either at any given time and get my mail and the mail being the same
>on both mainly for the reason if one was down. Anyone have a suggestion
>how I could accomplish this?
I'm not sure about the perfect mechanism to achieve this. I think the
best workable solution at this moment is to have a disk array with 2
SCSI interfaces, and connect it to 2 machines. You can't mount a volume
on both machines read-writeable, so it is impossible to connect to
"either one". But at least you have a "hot spare" in case something
happends with the OS or hardware of the first machine, and it is likely
that your cyrus databases are still ok.
I once just synchronised the cyrus spool directory with something like
unison, and that was not really the best solution. This bi-directional
synchronisation works for plain files, but with the database files this
causes more pain. I assume this works as soon as you reconstruct your
mailboxes on the failover machine at a crash: at least you have all the
data "stand by" on another machine.
It would be a bit better if there was something like offlineimap that
could synchronise a complete spool. With offlineimap you can synchronise
between two IMAP servers on user-basis. Maybe if offlineimap is
modified, or if you setup a configuration for each user, you can achieve
a situation with two identical mail-servers (where you can actually use
both at the same time).
I hope this kind of functionality comes into cyrus once; I assume it is
not there yet, I once asked this on the list before ;-) And maybe it
shouldn't be too difficult, since there is already a synchronisation
mechanism for NNTP in place, if I'm correct.
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