Wednesday, August 03, 2005

Recording skipping woes

For the last several months we have been dealing with small skips in audio recordings on our big recording Asterisk server. This is a P4 3.2GHz server with 2GB of Ram and has had several refittings with different drives/processors/motherboards over the last 6 months trying to fix the ast_channel_walk_locked WARNINGS that signify that a recording skip has taken place. This server has 7 T1s going into it and has two Digium TE405P cards and has on average 20 recordings concurrently with peaks no higher than 50. We have done recording like this in the past with no problems but when we added the second quad T1 card the recording skips started happening.

We have tried IDE, SCSI, SATA drives with no change over time and we have tried 3 different motherboards that didn't help either. I resolved to fix this without resorting to buying one of those lovely-but-obscenely-expensive solid-state hard drives($6000 for 8GB) so I did some research and talked to several people who have systems with many T1s and do a lot of recording. I ended up putting together a system with a SCSI 320 RAID card and two 15K drives along with two Sangoma a104 Quad T1 cards (because they use interrupts more efficiently than Digium cards). I did a lot of stress testing and haven't seen any skips so far in it's first day of operating, but only time will tell. I'll post again in another couple weeks to let you know if the skips have come back.