On 07/08/2012 12:49 PM, David Kentwood wrote:
Hi,
I want to setup spamassassin + clamav + postfix. Many internet guides use
Amavisd to integrate them together. However, my vps has only 516mb ram so I
don't want to install Amavisd unless it's really recommended. So would the
setup work well without using Amavisd? Would you recommend using Amavisd?
One thing to keep in mind are the various factors that influence memory
usage in spamassassin & clamav (and by how much).
For example (on a SLES-11 x86_64 box) clamd with just the stock ClamAV
rules has a RSS of 155MB, with a number of 3'rd party add in rulesets
(EG Sanesecurity, SecureiteInfo, etc) its RSS is over 500MB.
However the Clam + added rulesets has a hit rate that is 50x~100x higher
than just stock ClamAv rules
spamd's memory size is influenced by added rules and by scanned message
size. As spamd keeps in memory multiple copies of a message (the raw form,
the parsed 'full' form, the "cleaned" normalized form, etc) its memory
usage grows nonlinearly with message size. EG if you restrict spamd to
only scanning small (< 64KB) messages it might be no more than 100MB RSS
but when you feed it larger messages (say 350KB) it can easily hit
150MB RSS per instance.
So if you limit scanned message size you use less memory but then
bloated spams will slip thru. Also 3'rd party rulesets can be
quite helpful hitting fast mutating spams.
Depending upon your mail flow rate you may want to keep multiple spamd
children around. Each child uses up memory but multiple children help
thruput during bursts of incoming messages.
--
Dave Funk University of Iowa
<dbfunk (at) engineering.uiowa.edu> College of Engineering
319/335-5751 FAX: 319/384-0549 1256 Seamans Center
Sys_admin/Postmaster/cell_admin Iowa City, IA 52242-1527
#include <std_disclaimer.h>
Better is not better, 'standard' is better. B{
