[Asterisk-Users] Making asterisk distributed

[Sunrise Ltd]

Jeremy McNamara wrote:

> Trilogy India wrote:
>> I want to know, if someone has tried
>> to use clustering in asterisk to increase
>> its scalability and make it distributed??
>> If yes, how easy it is to cluster?
>
>Asterisk will not benefit from clustering.

It all depends on how one defines the term cluster.

There was a time not so long ago when clusters had little
or nothing to do with the kind of distributed parallel
processing that is so often (perhaps wrongly) called
clustering today. A more precise term would be grid
computing, not clustering.

DEC made the term cluster fashionable in the 80s with
their VAXcluster architecture. They pretty much coined and
owned the term back then. But those clusters where
designed for high availability and redundancy, not for
parallelising and distributing a compute job over multiple
CPUs.

Of course a VAXcluster would also increase scalability in
the same way that mirrored web servers do, simply because
they offer the same service on a single virtual network
address. Connections to the service are then workload
balanced between multiple nodes, but any given job is
always executing entirely on a single node, unless the
node goes down while the job is processing, in which case
it is failed over to another node to continue there.

In the hayday of the VAXcluster, if you used the word
clustering for any bundling of computing resouces that did
not meet the high standards set by VAXcluster technology,
most IT folks would have lectured you like "That's not a
cluster, it doesn't do proper failover, it doesn't have
quorum, it doesn't have distributed locking" etc etc.
Consequently, Unix vendors were extremely careful to avoid
using the word cluster. They would use terms like
workstation farm, compute farm, hot standby, etc etc.
However, during the 90s the term cluster has become a
catch all for anything that somehow bundles computing
resources.

In this sense, running multiple Asterisk servers to offer
the same service on a domain name representing multipe IPs
through round robin DNS or similar techniques is a form of
clustering, much more so than grid computing is, at least
in the original sense as it was defined by DEC. In the
same sense, TDMoE is a form of clustering.

Of course if your definition of clustering is grid
computing, then your statement is correct. Grid computing
does nothing for Asterisk.

rgds
benjk

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