[erlang-questions] RFC: mnesia majority checking

Ulf Wiger <>
Sat Dec 11 14:34:00 CET 2010

On 11 Dec 2010, at 14:20, Joseph Wayne Norton wrote:

> One last question for now.  How does this new majority checking feature treat tables having less than three replicas?

Well, a table with only one replica is always in majority. :)
For a table with two replicas, both must be up for the condition
to be met.

This makes sense if the idea is to avoid disaster if the network
is split. We cannot tell whether a nodedown is due to a partitioned
network or the other node crashing. If we want to be safe in such a
situation, we must avoid writing to the table. This really can't be done
safely on top of mnesia, since it will be a race.

Ulf W

Ulf Wiger, CTO, Erlang Solutions, Ltd.

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