Asterisk Scaling

I know that a lot of variables will go into the answer to this question, but I am hoping to get a little assistance in project planning.

I am trying to plan a project and hardware plan for an asterisk system that will be handling a large number of calls. What I am trying to work out is how the number of calls scale on hardware upgrades.

My initial Servers are some recommissioned HP DL380 G3 Dual 3ghz Xeon Processor Machines with 6 gig of ram. I am not looking specifically for the number of calls I can expect, but more like what type of increases I can expect under the following conditions:

If I upgrade ram from 6gig to 12gig
If I replace the DL380G3 with a DL580G3 (4 processors same speed and memory)

Now of the reasons (sort of). I am starting the project with the DL380G3s, and I am trying to determine my upgrade path while using the recommissioned hardware. I am currently removing the DL380s from production, and my next round of upgrades will have me replacing the DL580s and I want to know if it’s worth deploying the 580s to the Asterisk project


No one can say yes or no, you HAVE to say what load you are expecting and what they are to be doing, IE calll routing, Conference, hosted PBX.


Assume a basic script of extension picking up, going through an IVR then dialing outbound for normal voice call… With entire call recorded.

Assume a 100% load. I have no clue what the load will be, and not really trying to ask how many concurrent calls can be made, but rather what the scaling proportion would be between the two machines.

So in otherwords, if machine A has a maximum load of 100 calls, what would be reasonable to expect machine B to have for a maximum?

So in other words, Machine A is a DL380G3 dual 3ghz w/ 8g memory, Machine B is DL580G3 quad 3ghz w/ 8g memory.

What affects maximum concurrent calls best more memory, or more processors? How dows eache affect the number of concurrent calls?

Hi Have a read of … mensioning

I assume you will be running a separate recording server so that load wont affect anything.

what do you mean by “100% load” ? CPU load ?

But its better to run many machines at a lower load than one big one under heavy load


Apparently this is too complicated of a question to be answered without a million more questions…

ALL I want to know is what affects on a given performace upgrading the hardware will have… I dont need to post the dial plan, all the scripts and all the individual pieces of hardware specs to get there…

I have a given computer, it is a HP DL380G3 with 2 3ghx xeon processors and 8g of ram… ALL other things EXACTLY the same, If I change out the computer to a HP DL580G3 4 3ghz xeon processors and 8g of ram what propotionate increase in call volume should I expect? If I upgrade ram from 8g to 16g on either machine what proportionate increase should I expect?

Why would ANYTHING else matter???

And yes I started off by saying I already know there are a lot of other variables, I am not looking for an exact number, just an approximation so that I can PLAN a future path for hardware upgrades. I haven’t come close to maxing out a single computer, and I have 8 DL380s dedicated to this project. I also have 9 DL680s that are in production and scheduled for upgrades in the future, I want to make the best use of these servers before eventually retiring them to the dumpster.

If you know so much as to ask such a question and you have all this hardware available to you, I have a suggestion: run the tests yourself and post the results so you can educate all of us.


I am not trying to be confrontational. I also don’t have months of free time to sit around doing experiments, or going back and forth answering rediculously unimportant questions that the answers are already readily available to anyone with experience. I run a company, and I am attempting to PLAN the companies future paths.

I am not asking for exact numbers, nor am I asking for an exact answer. All I am asking is what RELETIVE impace increasing the number of processors on a given machine has. What reletive impact increasing the ram on a givem machine has. This isn’t that complicated of a question for anyone with EXPERIENCE working in a given area. I kinda thought I was asking in a forum where people might actually have that EXPERIENCE.

I understand that there are a lot of variables, and I have given the relevant information which is all calls are recorded, all calls are from SIP extension which goes through simple IVR and outbound to SIP Trunk. About the only pieces of data I haven’t given is the codec which is G729, and the current maximum calls which I have no idea.

The scripts/dial plans are SIMPLE recording is done on same machine as dialplan, calls are all VOICE…

I am not looking for FINITE numbers just reletive approximations to determine how to best utilize hardware as it’s retasked from job to job.

In other words this project has dual processor servers, I have quad processors that will be retasked in 6 months to a year and I want to know if the performance gain from dual processor machines to quad processor machines is worth the effort of retasking, or if I should retask the quads to another function in the company. This is a PLANNING excercise, not a science … 318862.pdf

Here is a link I just received from someone that gives me a general idea of what I was looking for. This link is intended to compare two compilers, but gives me an idea of what I needed to know which was how Asterisk scales through the addition of processors or cores…