[asterisk-users] High Availability with Asterisk

[adamk at 3a.hu]

My approach (in theory only, so please correct me if I'm wrong) would be 
to run asterisk on multiple boxes (one each).  A dedicated monitoring 
box (nagios?  custom scripts?) would perform frequent checks against the 
boxes (one of my previous projects one asterisk was using call files to 
demonstrate its health to another one).

If a box fails, I would simply redirect/reroute its traffic to another 
one, using network solutions.  Such as shutting down the production 
interface of a suspectedly failed asterisk box, having an idle one pick 
up its IP address, or using load balancing / routing / NAT to redirect 
the client's traffic to a standby box.

My approach is based on the experience that linux based HA tools are 
often not free, or don't scale well, or engineered to circumvent an 
error in a slower manner (eg. booting a second VM takes too much time). 
  However in the network world, there are well known protocols that were 
designed to take over in a matter of miliseconds.

I do understand that this would not provide 'session' data, so failing 
over to a different box would mean the need to re-register, could cause 
calls to drop etc.  This might be unacceptable for you.  As I said in 
the beginning, I haven't been building such systems, in my experience a 
dropped call is not that big of a deal, if it happens because the 
network cuts over to a different box.  This could be handled with a pair 
of frontend load balancers, where the number of asterisk boxes can be 
transparent.

hope this helps
adam