dovecot proxy/director and high availability design

[Chad M Stewart]

On 2015-07-21 02:54 PM, Laz C. Peterson wrote:
> The consensus seems to say no to RR DNS … I am going to take that into
> serious consideration.
> 
> With this proxy setup you describe, what would happen if HAProxy or
> Dovecot Proxy were to fail?

Multiple instances of each. I'll be using SmartOS as the base for my 
systems, so I'll be using ucarp, combined with haproxy should achieve 
what I'm after.  Given two client facing IPs, I'm thinking two instances 
of HAProxy+ucarp, each handling one IP.  Giving me active/active.  
HAProxy can hand off the connections to N+1 DP, the number of those 
would be based on redundancy plus load, thus my minimum would be 3.

Brainstorming your situation.... Install HAProxy (or similar) in each 
data center. Then use dovecot director to route users to the store they 
happen to be using.  In other words if the first connection from userA 
comes into data center 1 then it gets sent to MS1 in the same data 
center.  Their next connection comes into data center 2 (thinking mobile 
device vs their desktop), the dovecot director there would route the 
connection over to ms1 in data center 1.  Not that network efficient, 
but it might achieve what you want given your constraints too.


-Chad