Sizing machine for mailscanner

James Gray james at GRAYONLINE.ID.AU
Mon Mar 7 11:05:37 GMT 2005

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On Mon, 7 Mar 2005 08:04 pm, Koen Teugels wrote:
> If I get about 10000 mails /day in about 8 hours. What kind of machine
> do I need I i turn mailscanner + spamassassin + 3 antivirus programs?
> Thanks Koen

I set up a charity organisation recently with Linux (Debian Woody),
MailScanner, SpamAssassin 3.0.2 and ClamAV 0.83 on a Celeron 400 with 512MB
RAM and a single 40GB ATA66 drive[1].  They are handling a similar load to
what you describe at a rate of about 4sec/message.  System load hovers around
0.4-0.6 when a steady stream of mail arrives.

TO squeeze some speed out of this box, I set up a caching-only name server on
the same network and the MailScanner work directory is a RAM drive (128MB).
Other stuff I did to tweak things a little was compile a customised kernel
(for i686) and pretty much ripped out every service and package not essential
for a mail server - it's even running ssh via inetd (slow to connect but fine
once you're on).

Additional virus scanners don't seem to slow things down much in MailScanner
(I increased the mail gateway at work from McAfee only to
McAfee+ClamAV+Sophos+BitDefender and the increase in load and message
processing time was zero); the bottleneck is all the RBL's in SA3 and the
handling of large messages in SA3 - hence the caching name server.

MailScanner and the virus scanners are pretty quick.  The charity's mail
gateway is running  MailScanner with only 2 children too as that's about all
I could spare with the RAM drive.  3 children went awfully close to filling
physical RAM and I didn't want the box to start paging with only a single
(ATA - bleh) drive.  Paging kills performance.

Obviously this set up is a corner case and wont scale but it shows what can be
achieved with very "old" technology with some sensible selections and lean



[1] It was the box with the most grunt available - even then I pilfered RAM
from a desktop machine or two :P

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