Although we don't load balance it would be relatively easy to do if the incoming mailserver was really having trouble. We would just duplicate the machine using another mx record. With qmail, incoming SMTP concurrency would reach our max and the first machine would stop accepting new connections forcing connections to the secondary mx record. I guess it's not really load balancing - more like failover.
At 04:18 AM 10/28/2004, email builder wrote:
> We have two production mailservers running SA spamd. The first handles > about 5,000 incoming emails per hour, does spam filtering with SA and virus
Can I ask you how you load balance between the two machines (obviously if one handles 5000/hr and the other 2,500, it's not straight round robin)? I am not sure I understand how to fork requests between more than one machine when calling it through spamc.... (I don't understand how to configure this) ???
> filtering with qmailscanner and forwards the filtered mail to a server > handling the pop accounts. We're using SA 2.64 with Bayes, AWL, Razor and > about half of the RBL's. The machine is a 2.8Ghz P4 with 1.0GB RAM and SCSI > > hard drive. CPU usuage runs between 25-40% and system load runs 1.50 to > 2.20 with isolated spikes to 7.0. > > The second machine is a 2Ghz Athlon with 1.0GB RAM and an IDE drive. It > does spam and virus filtering with SA 2.64 and qmailscanner and also > handles POP3 sessions with vpopmail. We use Bayes, AWL, Razor and the same > RBL's. It handles approx 2,500 emails per hour (with peaks of 5K > emails/hour) and approx 2,000 pop3 sessions per hour (peaks of 5K > pops/hour). CPU usage runs about 20% with peaks to 50% and system load > averages 0.80 with peaks of 16.0. > > We are pretty satisfied with the above setup. We tried moving one of the > servers to SA 3.0 in order to use the new MySQL Bayes features but got > absolutely killed on CPU usage and system load - that lasted about a day > and we reverted to 2.64.
Wow, OK, I am starting to think I am actually not insane and that my system really isn't b0rked and is merely at its performance limit. Thanks Rick and Jeff for the reality check!
> We figure that we'd have to reduce the email load on each server by 50% in > order to use SA 3.0 and thereby need twice as many servers. However, we're > going to wait until the SA developers take the memory and load issues > seriously and fix the problem. Maybe if enough users complain they'll do > some high volume production test comparisons of 3.0 with previous versions > and sort out the problem.
This is disturbing. I'm surprised the CPU thing has not been a topic of conversation (I see the memory one is).... does anyone know if the developers are looking at this at all???
Thanks again!
> At 09:33 PM 10/27/2004, email builder wrote: > > > email builder wrote: > > > >>email builder wrote: > > > >>How much email are you processing ? > > > > > > > > > > > > Well, just the other day we had an average of 48 msgs/min (max > 255/min) > > > get > > > > run > > > > through SA. Can't say today yet because can't run our stats tools > until > > > the > > > > busy hours are over cuz SA is hogging the CPU. ;) > > > > > > Hi, > > > > > > Your CPU is over loaded. At 48 a minute it should run just ok on a 2.8 > > > Ghz machine, much over that it's going to start having problems. On > our > > > 2.4 Ghz (not HT) processor if I process over 35 a minute I start having > > > problems with load. > > > >I have two reactions to this: > > > >1) I like the glimmer of hope and the idea that throwing hardware at the > >problem can solve it > > > >2) Throwing hardware at problems is usually avoiding fixing the *real* > >problem. According to other posters on this list, my load is not > excessive > >for a modern-day 2.xGHz machine. I will have to re-read some messages, > but I > >believe responders to my posts on the "[OT] Email Servers" thread quoted > >similar machine specs and higher load than me and said they did not have > load > >problems. I'd love to hear that I am mistaken and that it's just a matter > of > >too little hardware, but I am skeptical... > > > > > I'd recommend upgrading to a dual server or perhaps putting in a second > > > server with round robin DNS (or if you can do it, a load balancer). > > > >We've been thinking about a multiple-machine email solution and have been > >wondering about architecture. Since SA seems to be the *only* email > server > >module that causes us grief (even amavisd-new/clamav is nicer to our > >machine!!), and although it seems strange not to go with a separate file > >server or database server machine (or to otherwise split up SMTP and IMAP, > >etc), I am starting to think (as you suggest) that just adding a separate > SA > >server is going to get us the biggest performance increase. What are > >people's opinions and experience setting up separate/multiple SA servers? > >Are there any good links for reading about such setups on the wiki or > >anywhere else? > > > > > SA is that CPU intensive, it really is. Maybe try adding RBL's in > front > > > of the MTA to reduce the number of messages you have to scan, that's > > > what we do. > > > >Ha! Yeah, this message rate is *WITH* something like 10 RBL's in Postfix > up > >front. W/out that, we'd *really* be drowning. :) > > > >Many thanks!
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Best Regards,
Jeff Koch, Intersessions
