Asterisk VoIP News

Wednesday, September 21, 2005

SUCCESS - 512 Simultaneous Calls with Digital Recording

This is a nice little article I found on the user list. I love reading people pushing technology to higher limits and releasing anything they came across in there observations.

Full Post:

"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"