[Dovecot] remote hot site, IMAP replication or cluster over WAN

Johan Hendriks joh.hendriks at gmail.com
Wed Nov 3 16:56:45 EET 2010

Op 3-11-2010 12:16, Stan Hoeppner schreef:
> Johan Hendriks put forth on 11/3/2010 3:32 AM:
>> Hello, i am working primarly with FreeBSD, and the latest release has a
>> service called HAST.
>> See it as a mirrored disk over the network.
>> You can install both machines with dovecot, and use the hast disk as the
>> data storage.
>> With CARP in the mix, when the master machine fails, it starts dovecot
>> on the slave.
>> This way you have a failover without user interference.
> 1.  How do you automatically redirect clients to the IP address of the
> slave when the master goes down?  Is this seamless?  What is the
> duration of "server down" seen by clients?  Seconds, minutes?
> 2.  When you bring the master back up after repairing the cause of the
> failure, does it automatically and correctly resume mirroring of the
> HAST device so it obtains the new emails that were saved to the slave
> while it was offline?  How do you then put the master back into service
> and make the slave offline again?
The servers work with an virtual ip.
Carp does this, i use it for the firewalls on our location.
Server 1 has ip adres, server 2 gets, and the 
virtual addres is
The clients connect to the virtual address, and contact the 
machine wich is master at that moment.

I do not know how the rebuild goes with hast, if the master provider 
goes down, like i said, i need to try and test it.
Maybe an question on the freebsd-fs mailing list will answer this.

More about HAST http://wiki.freebsd.org/HAST
More about Carp http://www.freebsd.org/doc/nl/books/handbook/carp.html

Johan Hendriks

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