Debugging and resolving high loadavg when running MailScanner
Steen, Glenn
Glenn.Steen at AP1.SE
Wed Feb 16 14:05:25 GMT 2005
Sre, and I'm not saying Rich _don't_ have a problem, just that what
he's shown so far don't really indicate a problem, and that he should
take advantage of the usual brew of tools to determine if he really
does have a problem (you know... sar, vmstat, iostat, top ... whatever).
-- Glenn
> -----Original Message-----
> From: MailScanner mailing list
> [mailto:MAILSCANNER at JISCMAIL.AC.UK] On Behalf Of
> Your-First-Name Your-Last-Name
> Sent: den 16 februari 2005 14:46
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Re: Debugging and resolving high loadavg when
> running MailScanner
>
>
> Just for information. I had high cpu usage and high load
> average and I found the problem
> was in mailscanner-mrtg process. Upgrading mailscanner-mrtg
> solved my problem.
>
> []s Borda.
>
>
> > Excuse me, but why are you "hung up" on loadfactor as a performance
> > meter?
> > It is just the average run queue size (averaged over 1, 5 and 15
> > minutes), and as such is meant
> > to vary.
> >
> > You say you have a 2 CPU system, in which case (with a "SMP capable"
> > kernel) you'd be fine
> > with anything up to 2 in a "sustained load" (meaning more than in
> > transient peaks).
> >
> > Add to this that processes in "non-interruptible wait"
> (usually for IO
> > resources) add an unconditional
> > 1 (one) each, it is not at all surprising that the load goes a bit
> > beyond your "CPU count" when you
> > have a larger batch of messages coming in.
> >
> > Unless you perceive true slowdowns, you don't really have a
> problem with
> > that.
> >
> > Now, the swap bit _could_ be an indicator of true
> problems... You say
> > you use it for other things than
> > as a mailhub... So you might be in a slightly memory starved state,
> > easily determined via vmstat or sar,
> > if you have a fair amount of ongoing swapping.
> > But using swap on a system that runs for an extended period
> of time is
> > usually not an indicator of
> > problems in and of itself, it is the actual moving to/from swap of
> > frequently used memory slices that'll
> > be a killer.
> > If you can determine that you have this situation, you have only two
> > venues: reduce the RAM usage
> > (by reducing what the machine does), or add more RAM.
> >
> > Nothing you've said so far indicate that you do have a
> problem... Does
> > the machine occasionally
> > slow down in a perceptible and measurable way? Does
> MailScanner report
> > huge batches?
> >
> > I'd like to recommend the excellent "swordfish book" from o'rielly
> > (Systems performance tuning).
> > Even though it is geared toward Solaris primarily and linux (2.4)
> > secondarily, it has a lot of general
> > good tips (and tool usage tips that are rather generic for
> most unices).
> >
> > -- Glenn
> >
> > -----Original Message-----
> > From: MailScanner mailing list
> > [mailto:MAILSCANNER at JISCMAIL.AC.UK] On Behalf Of Richard Curtis
> > Sent: den 16 februari 2005 13:04
> > To: MAILSCANNER at JISCMAIL.AC.UK
> > Subject: Re: Debugging and resolving high loadavg
> when running
> > MailScanner
> >
> >
> > I am not using either... running
> > spamassassin -D --lint -p
> > /etc/MailScanner/spam.assassin.prefs.conf says there are
> two problems -
> > but the two problems appear to be that razor and pyzor are not
> > installed..
> >
> > The load is sitting at around 0.5 at the moment -
> but when I was
> > looking about 5 minutes ago it shot to 5.0 when a large
> batch of email
> > came in.
> > I am wondering if I need to do something with the number of
> > children. I currently have it set to 10 - based on the
> reccomendation
> > of 5 per cpu.
> > The other thing I think might be related to my
> problems are the
> > fact that the system is using a fair amount of swap - would that
> > contribute to the load ?
> >
> > Rich
> >
> > Are you using razor or pyzor in that setup and does
> >
> > spamassassin -D --lint -p
> > /etc/MailScanner/spam.assassin.prefs.conf
> >
> > show any problems with either of these?
> >
> > If so,
> >
> > razor-admin -discover
> > pyzor discover
> >
> > might be useful (I've put them in a cron job here).
> >
> > Cheers,
> >
> > Phil
> >
> > ----
> > Phil Randal
> > Network Engineer
> > Herefordshire Council
> > Hereford, UK
> >
> >
> >
> > _____
> >
> > From: MailScanner mailing list
> > [mailto:MAILSCANNER at JISCMAIL.AC.UK] On Behalf Of Richard Curtis
> > Sent: 16 February 2005 11:33
> > To: MAILSCANNER at JISCMAIL.AC.UK
> > Subject: Debugging and resolving
> high loadavg
> > when running MailScanner
> >
> >
> > Hi All,
> > I have been running MailScanner (Version
> > 4.35.11) for some time, but over the last 2 -3 weeks, my loadavg has
> > gone from ~0.10-0.20 to as high as 4. This may not seem
> high to some,
> > but as I have other services on this box I want to try to reduce the
> > load.
> > The box runs httpd,
> sendmail/MailScanner with
> > clamav, radius and pop. There are multiple hosted domains on the
> > server.
> > The box is a dual AMD Athlon MP
> 1200 with 512MB
> > RAM.
> >
> > All mail is scanned through MailScanner for
> > virus's, but only a small number of the domains (low
> traffic ones) have
> > SpamAssassin enabled in MailScanners configs.
> > I have to admit that I am a bit
> confused by some
> > of the MailScanner config options - for example, the
> effects of "Deliver
> > In Background = yes" and "Delivery Method = batch".
> >
> > By setting the delivery method to
> queue, what
> > kind of impact on delivery time can I expect ? Will this have a
> > significant effect of lowering the load ?
> >
> > One other question, I note from
> looking through
> > the logs, I see entries like:
> > Feb 16 11:25:32 lancelot
> MailScanner[7544]: New
> > Batch: Scanning 1 messages, 1720 bytes
> > Feb 16 11:25:32 lancelot
> MailScanner[7544]: MCP
> > Checks completed at 1720 bytes per second
> > Feb 16 11:25:32 lancelot
> MailScanner[7544]: Spam
> > Checks completed at 1720 bytes per second
> >
> > Now what confuses me here is that I have MCP
> > checks and Spam checks set to off for this mail domain - so
> why are the
> > checks happening ?
> >
> > Any suggestions on performance tuning of
> > MailScanner, or possible sendmail config tweaks would be greatly
> > appreciated.
> >
> > Regards
> >
> > Richard
> >
> >
> > --
> > No virus found in this outgoing message.
> > Checked by AVG Anti-Virus.
> > Version: 7.0.300 / Virus Database: 265.8.8 -
> > Release Date: 14/02/05
> >
> >
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> > ------------------------
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> jiscmail at jiscmail.ac.uk
> > with the words:
> > 'leave mailscanner' in the body of
> the email.
> > Before posting, read the MAQ
> > (http://www.mailscanner.biz/maq/)
> > and the archives
> > (http://www.jiscmail.ac.uk/lists/mailscanner.html).
> >
> > Support MailScanner development -
> buy the book
> > off the website!
> >
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> > words:
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> > Before posting, read the MAQ
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> > and the archives
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> >
> > Support MailScanner development - buy the
> book off the
> > website!
> >
> >
> > --
> > No virus found in this incoming message.
> > Checked by AVG Anti-Virus.
> > Version: 7.0.300 / Virus Database: 265.8.8 - Release
> > Date: 14/02/05
> >
> >
> >
> > --
> > No virus found in this outgoing message.
> > Checked by AVG Anti-Virus.
> > Version: 7.0.300 / Virus Database: 265.8.8 - Release Date:
> > 14/02/05
> >
> >
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> > Before posting, read the MAQ
> (http://www.mailscanner.biz/maq/)
> > and the archives
>
> > (http://www.jiscmail.ac.uk/lists/mailscanner.html).
> >
> > Support MailScanner development - buy the book off
> the website!
> >
> >
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> > 'leave mailscanner' in the body of the email.
> > Before posting, read the MAQ (http://www.mailscanner.biz/maq/) and
> > the archives (http://www.jiscmail.ac.uk/lists/mailscanner.html).
> >
> > Support MailScanner development - buy the book off the website!
> >
>
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>
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