Performance with postfix

[Alex Broens]

On 4/2/2009 4:52 PM, JC Putter wrote:
> Hi i am busy testing what load my mailscanner box can handle.
> 
> i am running an intel 2.4Ghz with 1GB RAM and a normal SATA HDD drive using Postfix as MTA all RBL's are in SA al running on Centos 5.2
> 
> i am using smtp-source to test sending 2000 messages at once and i not getting the results i was hoping for it, after 24 min of running there are still 1300 messages in the queue.
> 
> is the normal or bad, postfix is a fast mta, i also noticed that mailscanner scans messages in batches of 30, and it really takes a long time for the 30 messages to be placed back in the queue.
> 
> vmstat
> procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
>  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
>  0  0 187204  43488  19036  65140    1    1     7    23   73    7  5  0 94  0  0
> 
> again am i asking too much from the hardware or is there something i can do to increase performance? '
> 
> i am using a caching dns server and added 
> 
> none /var/spool/MailScanner/incoming            tmpfs    defaults       0 0
>  
> in fstab

If you have little RAM, using tmpfs for MS's work is contraproductive.
Your swap usage show that what you could gain using tmpfs you loose by 
swapping - and swapping on a single disk plus all the queue I/O will hog 
the box.

On a *busy* box, using tmps with 4GB or less will cause it to swap and 
work against you.

Also try using smaller batches and possibly less threads to give the box 
some extra air.

More RAM isn't a large investment and every penny worth.

my 2 cents

Alex