Betr.: Recommended hardware spec 20000 users

[Arjan Melein]

>>> Op 22-4-2010 om  4:28  is door Neil Wilson <neilw at dcdata.co.za> geschreven:
> Hi guys,
> 
> I need some advice please,
> 
> What are your recommendations for hardware for a server that does Spam 
> scanning with SA, Clamav scanning, running postfix under Centos 5.4 and 
> logs in mysql and then forwards the emails on to an Exchange server for 
> +-20000 users?

Its not as much about the number of users but more about the actual e-mail volume .. if every user gets about 100 e-mails per day average you're talking 2.000.000 e-mails per day which is just over 20 per second.
Your biggest concern will probably be disk IO and not RAM, although your server will probably love you if you put 4Gb in.  (Dont forget that it needs to be 64bit for 8gb ram, aka OS re-install if its already installed)
One plus for more ram is that in theory you could use a ramdisk for temporary files, this should speed things up considerably and i *think* there is actually something like that mentioned in one of the MS wiki/faq's
A good thing to keep in mind is greylisting, if this server is actually on the internet side directly which I'm somewhat doubting as you said there is already some basic spam scanning done. Greylisting cut my e-mail volume that actually gets into MS by 4.

-
Arjan