[imp] High Availability / Load Balancing

[Lee]

>> We divide our users over two-box cyrus imap clusters. Each segment of
>> our users resides on a primary box with a second hot spare waiting to
>> take over in case of failure. Each box has a live copy of the data
>> using drbd. The boxes then monitor each other using linux-ha's
>> heartbeat. We havent had any problems with this setup thus far. We use
>> a dual perdition cluster to make the individual segments appear to be
>> one single server.
>>
>> L
>
> ooh, this looks nice, thanks!  i remember at one point people tried 
> this with
> linux md/swraid, but i don't think it was supported/recommended.  i 
> currently
> use solaris for my main server, linux for the backup, but wouldn't 
> hesitate to
> change to linux if this works well.  have you tried murder instead of 
> perdition?
>
> how do you set imp up for this?  do you look up per user and pick the 
> imap
> server from their record?  how does imp cope with failing over?
>

We're currently in the process of implementing redundancy/load 
balancing for imp. DRBD does not support load balancing (only one of 
the two cluster boxes can be active at any given time), so we're 
looking into DNS roundrobin with ip failover for IMP. Basically we set 
webmail.ourcompany.com to one of several webmail servers. Once the user 
gets to the webmail server they stay at that server (i.e. 
webmail2.ourcompany.com). We're going to try to implement heartbeart 
(linux-ha.org) to have one of the webmail machines take the ip of 
another machine if that other machine goes down.

Perdition seemlessly proxies users to the correct backend mailstore via 
an ldap lookup, so imp (and IMAP clients) just sees one mail server 
(mail.ourcompany.com).

L

> dom
>
> ------------------------------------------
> This message was penned by the hand of Dom