qmail hangs for while

Hello,

i'm using toaster 0.8.3. Sometimes (one per week) i have problem that
my server hangs for minute or two. I've limit 50 connections for smtpd
(local 20 and remote 10), all 50 connections are used. Server load is
about 50 - 100 and mostly is not responding. I setup connections limit
(timeoutconnect - 20, timeoutremote - 60, timeoutsmtpd - 60) it helps
little (dropping spammers and peple who only block free connections).
Computer is core duo 2 6400@ 2.13GHz with 2G ram. Emails are on
separate disc. Discs are sata with sw raid (mirror) using reiserfs
(need migrate to xfs). There is nothing unusual in logs (except no
activity for minute or two) - no errors, qmail is accepting
connections.

After this "timeout" spamassassin takes long time to process emails.

Where can be problem ? Weak CPU, bad power source, bad settings ?

Qmail is compiled with conf-spawn = 509, conf-split=101. Qmail-scanner
using st patch, using fast spamassassin. Spamassassin is 3.2.1. OS
Debian testing

Any advices welcome, thank you or help.

Lampa

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