[horde] Run Horde on a cluster?

[Kevin Konowalec]

I've currently got 12 front ends to horde.  The way I accomplish the  
load balancing/round-robining is to put 2 boxes running openBSD in  
front  of the cluster.  The boxes are set up to use CARP to listen  
for the "webmail" address and then using pf it routes the incoming  
connection requests to one of the 12 servers.  I use 2 openBSD boxes  
because they dynamically keep state between them so if one fails the  
other automatically takes over and the users are none the wiser.   
It's pretty slick.  The only problem I've encountered is that the  
CARP/pf combination can't tell if the machines they are routing to  
are alive (which can cause problems if they're sending users to a  
dead box).  I got around this by keeping all the machines in the  
cluster in a table and every minute I check to see which ones are  
alive and pop the ones that are down out of the table.  If users are  
connected when those machines go down PF will route them to the next  
machine when the one they were on is popped out of the rotation.

In terms of states I use memcached... that way it doesn't matter  
which machine a user is on - and it doesn't matter if in the middle  
of the session they get reassigned to a different server... they  
never know the difference.

Kevin


On Feb 2, 2007, at 10:39 AM, Chris St. Pierre wrote:

> I've got two machines running Horde; currently, I just direct users to
> one or the other with a quick script.  I'd like, however, to use the
> same CNAME to access both of them with a poor man's round-robin DNS
> load balancer.
>
> To this end, I've set the cookie domain to '.nebrwesleyan.edu' (the
> domain of both machines).  I've also set both to use the MySQL session
> handler, so they can draw their session information from a common
> database.
>
> What more do I need to do to make this work?  Currently, logins to
> either server work, but sessions don't transfer to the other server.
> I'm not even sure what debugging tools to use; most of the various
> cookie viewer Firefox extensions I've tried have been of little to no
> use.
>
> Thanks!
>
> Chris St. Pierre
> Unix Systems Administrator
> Nebraska Wesleyan University
> ----------------------------
> Never send mail to thobrux at nebrwesleyan.edu
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Kevin Konowalec
Web Systems Administrator
Academic Information and Communications Technologies (AICT)
University of Alberta

Phone:  (780) 492-3168
Fax:  (780) 492-1729

kevin.konowalec at ualberta.ca


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