[erlang-questions] Re: how to scale into the cloud using process? example computing simple average

Ulf Wiger <>
Sat May 30 15:17:56 CEST 2009


----- "Ulf Wiger" <> wrote:

> FWIW, the AXD 301 used a somewhat similar arbitration 
> mechanism: each node tried to ping itself through the 
> switch core.

For newcomers who haven't studied the ancient scrolls
about the AXD 301, one particular 'feature' of that 
system was that the control processors communicated 
via the very ATM switch that they were controlling.
As a consequence, if the ATM device boards were unstable
(which could happen during some phases of development),
partitioned network could occur daily, or even 
many times a day. Since I was in charge of writing the
cluster controller and solving the issues with mnesia
during that time, I recall those periods vividly.

The AXD 301 *did* recover automatically from partitioned
networks, and had to, since it was usually installed in
very remote locations (still is, I should say, since it
is being sold and used to this day.)

I submit this as proof that it is *not* impossible to 
recover automatically from partitioned networks when 
using mnesia. I think that there should be some behaviour
for resolving it using an observer, and a default 
algorithm for those who don't want to roll their own.

But there's no need for hacking mnesia in order to provide
that.

BR,
Ulf W
-- 
Ulf Wiger
CTO, Erlang Training & Consulting Ltd.
http://www.erlang-consulting.com


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