[Asterisk-Users] Large Asterisk Setup (~500 Concurrent Calls + Scalability)

[Matt Roth]

Daniel,

I would be interested to hear if anyone knows of a method to completely 
offload the Monitor command from the master server.  It is the missing 
piece of the puzzle to optimizing the digital recording process.

I'm assuming that the CPU usage you are referring to would be incurred 
due to converting the input and output packets from their codec to WAV 
format.  Please correct me if I'm wrong in that assumption.  I see the 
benefits of offloading that CPU usage to another machine, but I'm not 
sure if it's possible or how to implement it if it is. 

One benefit of the design that you overlooked is the offloading of disk 
I/O.  In this application that may not make a big difference, but it 
does allow us to do the mixing and compression to MP3 on a separate 
machine.  Both of those activities are CPU intensive.

You're correct that if we instructed the Monitor command to mix the 
files the mixing would occur on the master server.  I looked at the 
documentation and source (res_monitor.c) of the Monitor command to 
confirm that the default behavior is to NOT mix the files.  The options 
argument must contain the character 'm' for the mixing to occur.  We 
will be executing the Monitor command WITHOUT mixing, then running a 
periodic process on the Digital Recording Client to mix the files and 
compress the result to an MP3.

Thanks for your interest,

Matthew Roth
http://www.voip-info.org/tiki-index.php?page=Running%20Asterisk%20on%20Debian


Daniel Salama wrote:

> But it seems to me that the load of the Monitor command will remain in 
> the master server. The only thing you are really offloading is the 
> saving of the media stream which should have minimal impact. My 
> concern is that, with a busy installation, issuing too many Monitor 
> commands may "overload" CPU usage and have a direct effect on the 
> quality of the conversations. Are my assumptions wrong?
>
> When you tell the Monitor command to combine the resulting .wav files, 
> that will also be executed in the master server, which should add to 
> its load. Unless you tell the Monitor command NOT to combine the audio 
> files and you run that as a separate "croned" processed in the client 
> server which will also execute lame after soxmix.