[VoiceOps] Load balancing
abalashov at evaristesys.com
Fri Nov 6 21:53:34 EST 2009
John Todd wrote:
> I, for one, would be very interested to see anyone's results with the
> logically extreme version of "keeping state", meaning keeping media state.
> Asterisk can't perform failover between two discreet systems and
> maintain media state, if media is indeed being handled as a B2BUA and
> RTP relay. We (Digium) have been asked a few times about it, but the
> engineering effort is much much larger than the payoff and nobody from
> the open-source community has stepped forward with any code. The amount
> of synchronization data that would have to be exchanged between two
> systems running RTP and signaling is large. VERY large. That's not to
> say it can't be done, but I just haven't seen it done even with VMWare
> or other VM-based systems which may claim to be able to synchronize
> instances between chassis platforms.
> Most failures aren't hardware or chassis-based; they're software-based,
> so duplicating corrupted memory structures between two machines will
> give you (surprise!) two dead machines, or two dead apps on two machines
> regardless of the application being used. So this has limited use.
> Anyone who has code that relays minimal state WITHOUT mirroring the
> whole app/system so that two instances of (for instance) Asterisk could
> be synchronized without shared fate... I'll be very VERY interested in
> that. :-)
> So: has anyone out there done this with any RTP-capable systems running
> on Linux (Asterisk or otherwise)? If so, can you post notes and
> operational techniques?
I believe this effort is a specious and misguided waste of time, and
the interest in it is principally the expression of the following
deficiencies in the thought process of those doing the asking:
(1) Exaggerated, megalomaniacal perceptions of the relative importance
of four-9s vs. nine-9s uptime, and with it, lack of cursory
accompanying understanding of the Pareto principle;
(2) Lack of non-superficial comprehension of how the technology works,
which you have covered quite well with your post.
These are not satellite guidance systems. That level of failover is
simply unnecessary, although I have met more than one proud ITSP owner
who is prepared to solicit proposals for magic.
Alex Balashov - Principal
Web : http://www.evaristesys.com/
Tel : (+1) (678) 954-0670
Direct : (+1) (678) 954-0671
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