tuning Load Average for sendmail
in [Sendmail]
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From: RICCARDO on 13 May 2010 04:11 I'm using sendmail 8.12.10-1.1.1 and amavisd (with linked uvscan) for my mail server, which process about 700 mail messages a day.There is no other software on this mail server... In maillog files I can see "rejecting connections on daemon MTA: load average: XX" where XX is a number among 12 and 36. It occurs in a changeable time, 40รท 240 messages of rejecing connections" a day. My sendmail.cf says: #O QueueLA=8 #O RefuseLA=12 #O DelayLA=0 Can I modify it in this way ? What do you think ? #O QueueLA=20 #O RefuseLA=36 #O DelayLA=0 Or I can try to disable uvscan process to reduce load average ?
From: David F. Skoll on 13 May 2010 22:31 RICCARDO wrote: > #O QueueLA=8 > #O RefuseLA=12 > #O DelayLA=0 The Sendmail defaults are utterly inappropriate for Linux. I use: O QueueLA=1000 O RefuseLA=500 Or in .mc language: define(`confQUEUE_LA',`1000')dnl define(`confREFUSE_LA',`500')dnl In other words, I don't want sendmail to stop, regardless of load average. And I *certainly* don't want it queueing, but not delivering, if the load average is high. I have seen Linux boxes with load averages over 200 happily processing mail. Regards, David.
From: Per Hedeland on 14 May 2010 04:41 In article <66f9a$4becb619$d1d97a75$29567(a)PRIMUS.CA> "David F. Skoll" <dfs(a)roaringpenguin.com> writes: >RICCARDO wrote: > >> #O QueueLA=8 >> #O RefuseLA=12 >> #O DelayLA=0 > >The Sendmail defaults are utterly inappropriate for Linux. I use: > >O QueueLA=1000 >O RefuseLA=500 > >Or in .mc language: > >define(`confQUEUE_LA',`1000')dnl >define(`confREFUSE_LA',`500')dnl > >In other words, I don't want sendmail to stop, regardless of load >average. And I *certainly* don't want it queueing, but not >delivering, if the load average is high. This is an important point - whether Linux or not, and regardless of the absolute size of the numbers, on a dedicated mail server you always want to have QueueLA higher than RefuseLA. The defaults are from an ancient time when processing mail was typically just one of many tasks on a general-purpose server, and you didn't want it to impact more "interactive" functions at times of high load. If the load is *caused* by mail processing, having QueueLA lower than RefuseLA will just make things worse. --Per Hedeland per(a)hedeland.org
From: Andrzej Adam Filip on 14 May 2010 06:12 per(a)hedeland.org (Per Hedeland) wrote: > In article <66f9a$4becb619$d1d97a75$29567(a)PRIMUS.CA> "David F. Skoll" > <dfs(a)roaringpenguin.com> writes: >>RICCARDO wrote: >> >>> #O QueueLA=8 >>> #O RefuseLA=12 >>> #O DelayLA=0 >> >>The Sendmail defaults are utterly inappropriate for Linux. I use: >> >>O QueueLA=1000 >>O RefuseLA=500 >> >>Or in .mc language: >> >>define(`confQUEUE_LA',`1000')dnl >>define(`confREFUSE_LA',`500')dnl >> >>In other words, I don't want sendmail to stop, regardless of load >>average. And I *certainly* don't want it queueing, but not >>delivering, if the load average is high. > > This is an important point - whether Linux or not, and regardless of the > absolute size of the numbers, on a dedicated mail server you always want > to have QueueLA higher than RefuseLA. The defaults are from an ancient > time when processing mail was typically just one of many tasks on a > general-purpose server, and you didn't want it to impact more > "interactive" functions at times of high load. If the load is *caused* > by mail processing, having QueueLA lower than RefuseLA will just make > things worse. You are most likely right in *most* cases but I would not dare such "too simple statement" - there are exceptions (e.g. with "costly" local mailer forking one process per recipient under multiple recipient load). For postmaster chasing "simplicity" sendmail is hardly ever the preferred choice nowdays, is not it? :-) -- http://open-sendmail.sourceforge.net/ http://anfi.homeunix.org/ It's getting harder and harder to think out loud. One of these days someone's gonna go off and kill Thomas a'Becket for me... -- Larry Wall in <199709242015.NAA10312(a)wall.org>
From: Per Hedeland on 14 May 2010 17:33 In article <6os172tpw4+A5E(a)susan.huge.strangled.net> Andrzej Adam Filip <anfi(a)onet.eu> writes: >per(a)hedeland.org (Per Hedeland) wrote: >> In article <66f9a$4becb619$d1d97a75$29567(a)PRIMUS.CA> "David F. Skoll" >> <dfs(a)roaringpenguin.com> writes: >>>RICCARDO wrote: >>> >>>> #O QueueLA=8 >>>> #O RefuseLA=12 >>>> #O DelayLA=0 >>> >>>The Sendmail defaults are utterly inappropriate for Linux. I use: >>> >>>O QueueLA=1000 >>>O RefuseLA=500 >>> >>>Or in .mc language: >>> >>>define(`confQUEUE_LA',`1000')dnl >>>define(`confREFUSE_LA',`500')dnl >>> >>>In other words, I don't want sendmail to stop, regardless of load >>>average. And I *certainly* don't want it queueing, but not >>>delivering, if the load average is high. >> >> This is an important point - whether Linux or not, and regardless of the >> absolute size of the numbers, on a dedicated mail server you always want >> to have QueueLA higher than RefuseLA. The defaults are from an ancient >> time when processing mail was typically just one of many tasks on a >> general-purpose server, and you didn't want it to impact more >> "interactive" functions at times of high load. If the load is *caused* >> by mail processing, having QueueLA lower than RefuseLA will just make >> things worse. > >You are most likely right in *most* cases but I would not dare such >"too simple statement" - there are exceptions (e.g. with "costly" local >mailer forking one process per recipient under multiple recipient load). You avoid that cost whether you queue or refuse - but as long as you keep queueing in an overload situation, you keep causing load from that processing, and keep building up future load that will hit you when you start processing the huge queue - if you ever get below QueueLA, that is. As you just quoted Nick's book in another post, go read what he has to say on the subject... (and it wasn't new wisdom when he wrote it). --Per Hedeland per(a)hedeland.org
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