High-Availability IMAP server

[David]

Hello,

I have a 'pseudo' High Availability SMTP system consisting in two servers 
running cyrus 2.2.5.

The main problem I have is that only one of the two nodes can access to the 
mailboxes in order to keep the integrity of the cyrus databases despite the 
filesystem (GFS) has support to allow to two different servers access in R/W 
mode.

I've read about cyrus-murder which allows to distribute mailboxes along 
different servers but if the server that has the mailbox for user at domain.com 
goes offline, this mailbox is not available.

With maildir/mailbox format, there is no additional integrity mechanism so any 
server with R/W access to the filesystem can provide the mailbox via 
POP3/IMAP, etc.

Is there any way to achieve this goal using cyrus? Which is the best approach 
to this scenario? Run daily imapsync via cron and a Load Balancer forward the 
requests to the active one? 

Any help would be appreciated.

Regards,
David