Thanks Daniel,
We may end up replicating your tests in order to confirm some of your results. I don't know if it will be anytime soon, because we don't have the hardware yet. Regardless, I will share my results with the list.
Anyone out there have any ideas on why the NFS mount affected call quality? It seems backwards, since it should have relieved some of the load from the Asterisk machine.
Matthew Roth http://voip-info.org/tiki-index.php?page=Running%20Asterisk%20on%20Debian
Daniel Salama wrote:
Sure.
I setup a small lab on a machine with 4 T1s and 36 agents logged in. The system was configured to Monitor all outbound calls as well as monitor all calls distributed by Queue app (monitor-format setting in queues.conf).
When recording to local disk, everything was working fine. Agents were busy 99.5% and there were at least 30 calls waiting in Queue to be distributed. Average call conversation length was about 7.5 minutes.
Then I mounted /var/spool/asterisk/monitor via NFS using 10/100 Fast-E.
The moment we pushed the load on the Asterisk machine, everything worked for about 40 seconds. Then call quality started suffering significantly. Chopped audio. Bad audio. No audio. Good audio. You could imagine. So we stopped the test.
Then we unmounted the NFS drive and repeated the test again. Everything worked fine again.
The machine we tested asterisk on is a dual Xeon 3 GHz with 2G RAM. During all tests, CPU utilization was about 55% on the average (for each CPU). Memory usage was under 1G.
I would say I need to try more troubleshooting. Maybe there was congestion on the Fast-E, although preliminary analysis indicates there were no CRC errors, collisions, or packet loss.
The NFS machine was completely idle.
Last, we repeated the test over a 1 hour period. This time, Monitor was recording on local drives and we were copying files every 15 minutes with a background process (perl script) to NFS mount point. Everything worked fine as well.
I don't know if these tests are conclusive yet. However, from the results so far, I would recommend staying away from recording to NFS mounted point. I will continue running simulations to see if anything else can be identified.
Thanks, Daniel
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