Timo,
-----Original Message----- From: dovecot-bounces+brandond=uoregon.edu@dovecot.org [mailto:dovecot-
The company here in Italy didn't really like such idea, so I thought about making it more transparent and simpler to manage. The result is a new "director" service, which does basically the same thing, except without SQL database. The idea is that your load balancer can redirect connections to one or more Dovecot proxies, which internally then figure out where the user should go. So the proxies act kind of like a secondary load balancer layer.
This looks very cool! We run a basic two-site active-active configuration with 6 Dovecot hosts in either location, with an Active/Standby load balancer cluster in front, and a cluster of geographically distributed NFS servers in the back. I'm sure I've described it before. We'd like to keep failover as simple as possible while also avoiding single points of failure. I have some questions about the suggested configuration, as well as the current implementation.
Does this work for POP3 as well as IMAP?
Is there any reason not to use all 12 of our servers as proxies as well as mailbox servers, and let the director communication route connections to the appropriate endpoint?
Does putting a host into 'directed proxy' mode prevent it from servicing local mailbox requests?
How is initial synchronization handled? If a new host is added, is it sent a full copy of the user->host mapping database?
What would you think about using multicast for the notifications instead of a ring structure? If we did set up all 12 hosts in a ring, it would be conceivable that a site failure plus failure of a single host at the surviving site would segment the ring. Multicast would prevent this, as well as (conceivably) simplifying dynamic resizing of the pool.
Thanks!
-Brad