Re: MySQL authentication

[Brian Candler <B.Candler at pobox.com>]

On Fri, May 02, 2003 at 04:06:29PM +0200, antonio at nambu.uem.mz wrote:
> If I had my webmail and pop3 users for mail authenticating on a 
> machine running FreeBSD with MySQL and doing the user 
> authentication on MySQL, would it be possible to have more than 
> 1000 users authenticating simultaneously provided I had enough 
> Memory and CPU?

Difficult question, depends on lots of things.

One thing to bear in mind is that you are unlikely to have 1000 users
"authenticating simultaneously". If you had 1000 users, each of which was
making a fresh POP3 or IMAP connection every 5 minutes (600 seconds) that
would be 1.7 authentications per second. I should think that your database
wouldn't have any difficulty with that, as long as it wasn't too busy doing
other things. Your database will presumably be doing other things than
authentication: for example, receiving incoming mail via SMTP will need to
do a database query for each received message as well, to know where to
deliver it.

The best thing to do, of course, is to test it. Build a test rig and apply
an increasing load of more and more POP3 connections (there's a program
called 'rabid' which can do this - http://www.coker.com.au/postal/ - or
it's easy enough to write your own in Perl or whatever if you install a POP3
client library) and see when it fails. You can then try tuning your database
and/or O.S. to improve performance.

To make your service more scalable, I'd suggest that you keep the database
on one box and the mail front-end machine(s) as other boxes. A good idea is
to have two ethernet cards on the front-end machines: one facing the world
with a public IP, and one on a private network where the database box sits.
This means the database is not routable from the Internet. If you decide to
run a shared NFS mail store then you can put your NFS server(s) on this
private network too, and scale the service by adding additional front-end
machines.

Regards,

Brian.

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