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

[Gottschalk, David]

My understanding of the dns_available settings was merely to check if DNS was working properly before it attempted to do DNS checks.

Do I not understand that setting correctly?

David Gottschalk

-----Original Message-----
From: mailscanner-bounces at lists.mailscanner.info [mailto:mailscanner-bounces at lists.mailscanner.info] On Behalf Of Julian Field
Sent: Thursday, July 12, 2007 2:46 PM
To: MailScanner discussion
Subject: Re: A very slow MS 4.62.2-3 & SA 3.2.1 & ClamAV 0.91 machine

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Alex Neuman van der Hans wrote:
> 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.
But if you switch off DNS lookups for SpamAssassin, you will severely damage its ability to detect spam. Better to diagnose your slow DNS lookups and switch it back on.

Jules

- --
Julian Field MEng CITP
www.MailScanner.info
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