A very slow MS 4.62.2-3 & SA 3.2.1 & ClamAV 0.91 machine

[Alex Neuman van der Hans]

Gottschalk, David wrote:
> I have five mail gateways. Here are a few things I've done that helped a lot.
>
> The item that made the biggest difference was changing 'Max Unscanned Messages Per Scan = 30' to 10, and changing 'Max Unsafe Messages Per Scan = 30' to 10 as well.
>
> I also increased my "Max Children" to 10, but I'm still working on tweaking that (only been running MailScanner in production for a week now).
>
> I had one machine that could not keep up with the volume of mail. I couldn't figure out why one machine was having trouble when the rest were doing fine. Soon I discovered that Spamassassin was causing a huge slow down on that one box. It was hanging for ever on checking if dns was avaiable or not. I set 'dns_available no' in the spam.assassin.prefs.conf file and things sped waaayyy up. I changed it on my other relays and it made a significant different on them as well, but not as much as the one relay that couldn't keep up with mail orginially. I still haven't figured out why it so greatly effected that one machine.
>
>   
I believe dns_available no might *affect* :-) machines that don't have 
local caching DNS enabled much more than those that don't. It's always 
been recommended to do this in order to minimize DNS lookup times for 
spamassassin.
> Hope that helps.
>
> Good luck.
>
> David Gottschalk
> Emory University Infrastructure Technology Services
> david.gottschalk at emory.edu
>
> -----Original Message-----
> From: mailscanner-bounces at lists.mailscanner.info [mailto:mailscanner-bounces at lists.mailscanner.info] On Behalf Of Quentin Campbell
> Sent: Thursday, July 12, 2007 11:37 AM
> To: MailScanner discussion
> Subject: A very slow MS 4.62.2-3 & SA 3.2.1 & ClamAV 0.91 machine
>
> I have a very slow mail gateway among the 4 that I have just upgraded.
>
> They all run MS 4.62.2-3, SA 3.2.1 and ClamAV 0.91 and should have identical configurations for MS and SA. MCP processing is done and it is the same on all 4.
>
> There were 211 batches of 30 messages each processed on the slow machine. Overall the average time to process each message is 15 seconds!
>
> The last two of these batches were processed by running MailScanner in debug mode. The average processing time for each message then dropped to between 2 and 3 seconds!
>
> I am trying to get a handle on why this machine is so slow. Any suggestions to help further my investigation are welcome.
>
> Quentin
> ---
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