MailScanner Max Children

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toddh
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MailScanner Max Children

Post by toddh » 26 Mar 2015 14:03

I am curious how EFA controls MailScanner Max Children

According to the MailScanner site
http://www.mailscanner.info/gettingthebest.html

MailScanner
Leave most things set at defaults.
Max Children = 4 x number of CPU cores. Each 5 children require 1GB RAM.

But it seems EFA Sets a limit of 10, or the equivalent of 2 cores of MS children.

But I believe I recall seeing a formula somewhere in the config where EFA could dynamically add/remove Postfix and MailScanner Processes as needed?

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shawniverson
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Re: MailScanner Max Children

Post by shawniverson » 26 Mar 2015 15:15

10 is just an arbitrary limit, you can set the threads as high as you want in MailScanner.conf

I am not aware of any dynamic scaling functionality in postfix/mailscanner.
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toddh
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Re: MailScanner Max Children

Post by toddh » 26 Mar 2015 22:01

After reading the forum I saw recommendations for running MailScanner Threads per Core anywhere from 1:1 to 4:1. When i tried to add more than 10 from EFA-Configure it of course would not let me so I was just wondering. Then I saw on the MailScanner site they said 5:1 and was really getting confused. :lol:

If I set it at 10 and there is no dynamic scaling why does EFA interface show the MailScanner Children changing. Am i looking at the wrong thing?

.

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pdwalker
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Re: MailScanner Max Children

Post by pdwalker » 27 Mar 2015 03:16

For that, you may want to look through the mailscanner forums and docs.

EFA is just a very nice bundling, integration and preconfiguration of various mail delivery and anti spam tools. While people in the forums may know the answer to a particular question, you may be more likely to find the answers to more technical question in the individual product forums, assuming they may have one.

Once I realized this, I was able to find the answers to my more technical questions a little faster.

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pdwalker
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Re: MailScanner Max Children

Post by pdwalker » 27 Mar 2015 05:35

If you look at page 141 of the MailScanner User Guide and Training Manual, you can see their recommendations.

So how many should you use? It'll depend on the workload and where the processes are contending for resources. I'd be inclined to go with 1 or 2 per CPU core (3 for hyperthreaded cores) and then watch/adjust from there. That's a personal preference and I have nothing concrete to back that up on. The Mailscanner recommendation of 5 to 7 may provide better performance/throughput. Test and find out.

As for why the number fluctuates, Mailscanner does appear to increase/decrease the number of active children running, depending on the active workload. It will not create more than the # of CPU * Max threads per core.

Does that help?

toddh
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Re: MailScanner Max Children

Post by toddh » 27 Mar 2015 14:01

Thanks the manual is very helpful. I see info about Max Child setting on page 125 but nothing on 141.

Looks like I have some reading to do... :)


when I set Max Children to 10, the web interface in EFA regular reports 16+ during load.


.

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pdwalker
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Re: MailScanner Max Children

Post by pdwalker » 27 Mar 2015 15:43

The page marked 125 is 141 pages in. There is another document added to the front of the PDF which throws off the page numbering.

As for the 16 processes, with a max of 10 set in EFA, I'm not sure. I'd have to dig in and look.

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darky83
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Re: MailScanner Max Children

Post by darky83 » 29 Mar 2015 16:47

From my personal testing i found out that in my cases just over 1 child per cpu gives me the best performance.
I try to use the formula like: <ammount of cpu's> * 1.25 and then round it up or down (< 0.5 = down, 0.5 = depends, > 0.5 = up)

So:
2 cpu = 2.5 = 2 childs
3 cpu = 3.75 = 4 childs
4 cpu = 5 = 5 childs
6 cpu = 7.5 = 7 ~ 8 childs
12 cpu = 15 = 15 childs

But it all depends, there is no hard working formula, above is an guidline that works in most of my cases.
Disk I/O, memory, physical host resource usage etc are all factors in play here.

Best thing I can recommend is to start with the above settings and play with it from there, you might need to tune it up or down in your case.

Also note that if you increase the children you will also need to increase the available memory.
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darky83
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Re: MailScanner Max Children

Post by darky83 » 29 Mar 2015 16:54

Also note that the mailscanner manual recommends more (5 i beleive per cpu?)

But efa does a bit more than just mailscanner so those recommendations should not be followed to the letter.
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shawniverson
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Re: MailScanner Max Children

Post by shawniverson » 29 Mar 2015 18:45

darky83 wrote:Also note that the mailscanner manual recommends more (5 i beleive per cpu?)

But efa does a bit more than just mailscanner so those recommendations should not be followed to the letter.
+1
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