[imp] Help Req. : Sizing a Horde\IMP system for 12,000 users

[Andrew Morgan]

On Mon, 9 Dec 2002, Martin Searle wrote:

> Hi,
>
> I work for the University of Kent in the UK and we are looking to
> replace our current Email client with a horde\IMP webmail system. I
> have been asked to research what sort of machine(s) is required to run
> the system, it maybe that a clustered approach would be better ?.
>
> Our current Horde IMP system shows excessive strain with about 2-3,000
> users logged in its a Sun Blade 100, 384mb, 9gb disk machine, which
> granted is not a very powerful piece of kit, it runs IMP v2.2.6. We
> have apache and Solaris 9 on the machine. This machine serves
> off-campus users mainly although some internal users have switched to
> it exclusively.
>
> Our current email system handles approx. 60,000 outgoing emails per
> day from a variety of clients.
>
> We do have a limited budget and we would like to continue to use Sun
> hardware. So does anyone have any thoughts or have first hand
> experience with setting up a system to handle more than 10,000
> concurrent users ? My gut reaction is too look at clustering and use
> spare space on existing servers.

You don't really say what you mean by 10,000 concurrent users...  Our
webmail system handles about 13,000 logins per day, but I don't have a
clue how many are logged in at a given time.  (Side topic: does anyone
know an easy way to track the number of currently logged in users?)
During the peak times of the day, we get about 35 hits per second on each
of our two webmail servers.

The two servers are Dell 2650s with dual P4 2.2GHz cpus, 1GB RAM, and two
18GB drives (mirrored) running Debian Linux 3.0 (Woody!).  We run Horde
2.1, IMP 3.1, Turba 1.1, and Kronolith 1.0.  A separate database server is
used for preferences and session storage.  The two webmail servers sit
behind a Foundry Networks ServerIronXL load balancer.  With our current
load, we could probably operate with only one of these webmail servers
running, but we planned for growth.

	Andy