Hi,
I am running a webserver with over 300 Domains on a 100Mbps data centre connection.
The Problem:
Recently i have had problems with Incoming email attachments freezing up qmail. I am under the full impression that it freezes up because qmail is waiting for the emails to be dealt with before it will move on. Also, when it freezes users trying to get email will get a timeout (POP3) & basically all activity stops & cpu % soars (Also affecting the rest of the servers services). Once the email is has passed through Qmail & delivered the server returns to normal operation & then must deal with 1 or 2 minutes (maybe more) of backlog.
Extra info:
- I am using Spamassassin but if i turn it off this problem still occurs so i don't believe it is Spamassassin related. I have it set to 5 child processes.
- I am running PLESK Control Panel
- CentOS 4.5
- 2Gb Ram which is running fine
- Dual Xeon processor
- conncurrencylocal is 50
- conncurrencyremote is 20
- queuelifetime is 604800
- timeoutconnect is 30
- timeoutremote is 120
- timeoutsmtpd is 300
- databytes is 31457280
- I am also running a remote service monitoring program (4PSA Server Controller) which shows this occurs when incoming data is high around 250KBps+, which when timed side by side with the maillog shows it was incoming mail that haults the server - everytime.
So all this comes back to the title of my question which referred to either:
- How do i control bandwidth (e.g. Incoming Port Bandwidth Control)
or
- A problem with my Qmail settings (which i have been raising and lowering daily to troubleshoot)
or maybe something i haven't thought of?
I have been searching for solutions on Incoming port bandwidth control and constantly come up with Hardware solutions. Does anyone know of a software solution to try and troubleshoot as i can't find one.
Thanks for your time & assistance :-)
Wayne.
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