[Linux-cluster] High availability mail server

[Gordan Bobic]

> the hard part of this is how to balance the users between MailA and MailB (and MailC , D, E). Changing the value of "mail_host" in user attr (if using a Directory Service) and moving user's email from one filesystem to another

You don't have to if you have Maildirs on GFS. Each user will have a Maildir subtree. All you need to do is ensure that user X goes to a fixed server(X). This will ensure that only that server ever holds locks on Maildir(X), thus ensuring that locks will have local RAM latency instead of network ping time.

If server(X) fails, another machine in the cluster will assume it's IP address and become it. On first access to the subtrees there'll be a latency penalty on the server that took over, but thereafter it'll run at local speeds, especially if you are running on DRBD rather than a SAN.

Gordan