[Freeswitch-users] HA clustering solution?

[Tom Warren]

Wow, this has turned into quite a debate.

I think HA could be the killer app that catapults FS into the
mainstream. Even if not full implemented today, laying the groundwork
to allow for call state synchronization with a standby box would be a
great leap ahead of any other platform I'm aware of.

Although not fully analogous, if you want to see an example of state
mirroring look at Cisco SNAT. This synchronizes NAT entries to a
standby router so that IP conversations are not reset when switchover
occurs.

Imagine running just two boxes and having a fully redundant and
mirrored configuration where when the primary box fails, the caller
hears only a momentary 'hiccup' then conversation continues on....

Tom


2008/8/27 James Green <james.green at stealthnet.net>:
> Łukasz Zwierko wrote:
>> External monitoring would be better, system might hang up, interface
>> could remain up.
>
> Wherein lay an additional problem. Should the system be under severe
> load, the "system" may appear to hang, indeed become unreachable
> temporarily. Do you remove the host or check for a flapping state? I
> think it best to say that architecturally there are lots of considerations!
>
>> In my opinion the state would have to be updated at all time. It can
>> not be assumed that the host will have time/means to transfer anything
>> to new-active host when the crash begins.
>
> Indeed, but I would prefer to know that the software developers had
> designed their modules / core with syncronisation in mind rather than as
> an afterthought.
>
>> I've seen a solution similiar to the one we talking about. Two hosts
>> were connected directly, and the active, updated the secondary all the
>> time, with sessions of active users (it was not voip solutions, it
>> was for GPRS traffic inspection). It was a proprietary solution -
>> Bytemobile MSSP. It a switchover occured (for any reasons), unstable
>> sessions got lost, active sessions remained active. The IP sharing
>> worked a bit differently than I described, as the machines exchanged
>> heartbeat, were not controlled by external monitoring.
>
> There comes a time where the degree of reliability needs to be weighed
> against commercial requirements. Unstable sessions being transferred in
> my opinion is in the "not worth it" category unless you have commercial
> reasons to spend development time on testing it. Banks have cash (well,
> they did...) open source tends to rely on goodwill :-)
>
>> It's hard but doable. More problem would be with restoring call states
>> in standby FS (including voice transcoded connections) . And what
>> about calls being served by external scripts? That's a real challenge!
>
> Walk before you can run! I do wonder if there is scope for thought given
> FS can act as a proxy itself...
>
> James
>
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