Update on debugging external test problems...

[Mark Thornton]

We have resolved the external tests problem by installing the djbdns caching
dns server (http://cr.yp.to/djbdns.html) on the amavisd/spamassassin relay
server. Prior to installation the log was showing TIMING reports of ranging
from 10000 to 50000 ms, with the average being about 18000 ms. If we enabled
any external test this was the result. Now all messages are processing with
TIMING results of 300 to 2600 ms with the average being about 1200 ms. Since
making the change our system has not fallen behind or been under any
significant strain at all.

The reason: apparently the dns load from the relay server was sufficient to
drive our primary dns server's cache into some form of corruption. It would
resolve local sites fine but not external sites until reset. As a result the
relay server was then failing over to the secondary dns server to complete
the external queries. Since the primary server was partially responding it
seemed to always get first crack but failed. The relay server could put the
dns server into this state in about 18 hours, but I had never seen this
before under normal usage. Looks like I need to work on the dns servers...

Mark Thornton
San Marcos Internet, Inc
512-393-5300




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[Ralf Hildebrandt]

Post by Mark Thornton
We have resolved the external tests problem by installing the djbdns
caching dns server (http://cr.yp.to/djbdns.html) on the
amavisd/spamassassin relay server. Prior to installation the log was
showing TIMING reports of ranging from 10000 to 50000 ms, with the
average being about 18000 ms. If we enabled any external test this
was the result. Now all messages are processing with TIMING results
of 300 to 2600 ms with the average being about 1200 ms. Since making
the change our system has not fallen behind or been under any
significant strain at all.

We've been using dnscache for ages now, and it never let us down.

Post by Mark Thornton
The reason: apparently the dns load from the relay server was sufficient to
drive our primary dns server's cache into some form of corruption.

BIND?

I made a test for DNS query time with and without dnscache:
Loading Image...
--
Ralf Hildebrandt (Im Auftrag des Referat V a) ***@charite.de
Charite Campus Mitte Tel. [phone]
Referat V a - Kommunikationsnetze - Fax. [phone]
AIM: ralfpostfix


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[Mark Thornton]

Nope, we have been using the MS dns on W2K Server. It has been working well
for us until now. Apparently it doesn't like the volume or repetetive use,
though the secondary server doesn't seem to mind. It gets less overall usage
though. I think I am going to install more rjbdns servers for customer use
and move the MS units to strictly hosting the external dns.

Mark Thornton
San Marcos Internet, Inc
512-393-5300


----- Original Message -----
From: "Ralf Hildebrandt" <***@charite.de>
To: <AMaViS-***@lists.sourceforge.net>
Sent: Thursday, May 29, 2003 10:40 AM
Subject: Re: [AMaViS-user] Update on debugging external test problems...

Post by Ralf Hildebrandt

Post by Mark Thornton
We have resolved the external tests problem by installing the djbdns
caching dns server (http://cr.yp.to/djbdns.html) on the
amavisd/spamassassin relay server. Prior to installation the log was
showing TIMING reports of ranging from 10000 to 50000 ms, with the
average being about 18000 ms. If we enabled any external test this
was the result. Now all messages are processing with TIMING results
of 300 to 2600 ms with the average being about 1200 ms. Since making
the change our system has not fallen behind or been under any
significant strain at all.

We've been using dnscache for ages now, and it never let us down.

Post by Mark Thornton
The reason: apparently the dns load from the relay server was sufficient to
drive our primary dns server's cache into some form of corruption.

BIND?
http://www.stahl.bau.tu-bs.de/~hildeb/postfix/querytimes.png
--
Ralf Hildebrandt (Im Auftrag des Referat V a)
Charite Campus Mitte Tel. [phone]
Referat V a - Kommunikationsnetze - Fax. [phone]
AIM: ralfpostfix
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[Ralf Hildebrandt]

Post by Ralf Hildebrandt
http://www.stahl.bau.tu-bs.de/~hildeb/postfix/querytimes.png

To clarify the x-Axis: I made 250 lookups, the x axis simply numbers
the lookups (lookup of addresslist[0] to lookup of addresslist[250])
--
Ralf Hildebrandt (Im Auftrag des Referat V a) ***@charite.de
Charite Campus Mitte Tel. [phone]
Referat V a - Kommunikationsnetze - Fax. [phone]
AIM: ralfpostfix


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