[hydra-dev] * Fault Tolerance vs High availability

[Marc Blanchet]

it is like security: each one has to put his requirements and do his 
risk assessments. And there is a wide variety of requirements in the 
market.

Usually, low-cost new providers/users to the market, which is where 
asterisk is good at, does not have the same requirements as more 
mature/large scale providers.

Therefore, a good architecture should accomodate users to enable or 
disable these kinds of features, based on their own assesment of the 
needs. because, yes, you are right, fault 
tolerance/high-availability/redundancy/... are often "expensive" 
(expensive not only counting the duplicated 
hardware/software/bandwidth/..., but everything around: complexity of 
operations, management, software development, etc...)

Marc.

Le 10-06-03 10:09, Ed Guy a écrit :
> Hydrates,
>
> During the meeting a couple months ago,
>
> there was considerable discussion about fault-tolerance.
>
> In my book,  Fault tolerance implies that if there is a system failure
> on a component that involves an active call, the call is migrated,
> without significant
> interruption, to another component.
>
> is this really a requirement??? Most carrier grade systems merely
> require high availability. i.e., if a
> component fails, a call may drop, but the next call must go through. (
> "fives-nines" or better of the time )
>
> Fault tolerant architectures are very expensive and inefficient, but,
> sometimes you cant afford any failure.
>
>
> /ed
>
>
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