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What are the limits / ideal capacity to add another MTE server?

Posted by ophirr on Sun, 02/24/2013

Hi All,
I'm on my first MTE server and currently reach up to 100 concurrent calls, 15% are mixmonitored,
rarely using conference calls.
almost no transcoding.
asterisk 1.8.15.1
dual quad xeon 1.8

what is the right time to set the next server?
can you guys share some experience?
when did you decide adding your next MTE server?


Submitted by rfrantik on Tue, 02/26/2013 Permalink

You can read thru the forums and you should see this question or one like it several times.

Do you really have 100 concurrent calls? or 100 call segments? The Asterisk status page generally shows segments... one in plus one out is a single call, 2 segments.

Theoretically, if you are running 1GB Etherenet interfaces and a low bandwidth codec, you can keep going till you run out of bandwidth... but that seems like a poor design.

We have started creating new MTE servers around the 350-500 user mark... This was primarily based on some advice from users in this forum. This benchmark has more to do with the human part of managing 500 users on a single server than it has to do with any technical limitations. We currently have 3 servers up and running... so far, so good.

Submitted by eeman on Wed, 02/27/2013 Permalink

the biggest limitation I saw hit early was on a system where they did not want to employ sip-proxies at the customer sites. To side-step NAT issues they told their phones to re-register every 60 seconds instead of every hour. When you look at the CLI of this behavior, you see lots of messages like registering sip/101@123.123.123.123:1044 and then the next minute it shows up again but now its port 1121 and so-on and so-forth. All the port hopping forces asterisk to constantly update the ASTDB for the registration table which is essentially a disk i/o process of updating a berkleydb file. So when the box had 1600 handsets on it, all registering every 60 seconds; that came out to be about 27 write sessions every second. The load average of the box hung out around 3.5 constantly. For them their threshold of when to get a new box happened around 1500 handsets. Without that design, they likely could have had 8000 handsets on that single server based on the way it was being utilized.

Submitted by ophirr on Wed, 02/27/2013 Permalink

so you are actually say that I can have 8000 registered extensions?
what about if 20% of the extensions are recorded?
what about having queue, conference rooms, faxes...
such activities should affects the decision?

I read in forums that 400 concurrent calls without transcoding is the maximum,
I use the munin to see how far it goes every week:

asterisk active channels max is 100
asterisk channels max is 63

which one means concurrent call?