[horde] horde supports load balancing?

[Andrew Morgan]

On Thu, 1 May 2003, Colin Devine wrote:

> Hello,
>
> Reviewing the mailing lists archives and documentation of horde I
> believe it is possible to have two versions of horde installed and
> functioning using DNS round robin load balancing.  Specifically I would
> have two machines sharing the same dns name for a Horde/Imp installation
> and using mysql as the session handler, and virtual filesystem for
> attachments.  Can someone confirm that this is possible, and perhaps
> give real world examples?  Thank you in advance for your time.
>
> --Colin Devine

Sure, this is easy to do.  You don't have to do anything special with your
Horde installation to support load balancing, except sharing the sessions
and/or filesystem for attachments.  I'd also recommend using rsync to keep
the two Horde installations in sync.

We use a hardware load balancing device (Foundry Networks ServerIronXL)
instead of DNS round robin.  DNS round robin will work fine, although it
won't gracefully handle a failed server and the load balancing is a little
rudimentary.  Still, if you don't have the money to buy a hardware load
balancer, it's a decent solution.

Our setup is two Dell 2650s running Horde behind the load balancer, with
sessions stored on a separate MySQL server.  There are three or four
different IMAP servers (for different email systems on campus), all on
separate servers.  The hardware load balancer has "sticky" sessions, so I
don't bother using a shared filesystem for attachments.  The only case
where this would be a problem is if one of the Horde servers goes down and
the user gets bumped over to the other server.  The SQL VFS stuff in Horde
seemed a little too new to try the last time I upgraded.

Hope this helps,

	Andy