[Asterisk-Users] SUCCESS - 512 Simultaneous Calls with Digital Recording

[Matt Roth]

List users,

Over the last few days we have been working with MCI's development lab 
to test our Asterisk setup.  We were using a piece of hardware called an 
Abacus 5000 that is capable of creating and terminating thousands of SIP 
calls.  Initially, we could not get past 64 simultaneous digitally 
recorded calls without having call quality issues including dropped 
calls.  We identified an I/O bottleneck and rectified it by digitally 
recording to a RAM disk.  Using this method, we were able to digitally 
record 512 simultaneous SIP-to-SIP calls with 100% call completion.

Our plan is to use the MONITOR_EXEC hook to call a custom program that 
will copy files to the hard disk at call completion.  This should be no 
problem when calling Monitor directly from the dialplan, but I need to 
know if there are any complications when digitally recording from 
app_queue or chan_agent.  If anyone has experience with using 
MONITOR_EXEC and MONITOR_EXEC_ARGS with these applications, your input 
would be greatly appreciated.  Digital recording seems to be the 
limiting factor when scaling an Asterisk system and we will share any 
advances we make with the community.

We also noticed some "Avoided initial deadlock" and "Avoided deadlock" 
warnings in the messages file that Asterisk generates.  Our 128 and 256 
simultaneous call tests each produced one of these warnings.  Our 512 
simultaneous call test produced 18 of them all within a 10 second span, 
each on a separate SIP channel.  Can anyone shed light on what these 
warnings mean, how they can be avoided, and if they are something to 
worry about.  They did not seem to affect the outcome of the testing in 
any way.

Details of our testing (hardware configuration, OS tweaks, system 
resource usage, reports from the Abacus 5000, etc.) will be made 
available over time.  Please bear with me, as I am working on a deadline.

Thank you,

Matthew Roth
InterMedia Marketing Solutions
Software Engineer and Systems Developer