Details
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Task
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Resolution: Done
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Major - P3
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None
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None
Description
To avoid confusion we need additional clarification on how our voting system works [checked with 2.4.2]:
In order for the node to be elected as PRIMARY in a replica set, it needs to collect just a majority of votes (not the votes from the majority of nodes).
That being said, if you have 3-node replica set with votes
{15,1,1}and eventually it becomes split:
{15}|
{1,1} - then the one with 15 votes will elect himself as PRIMARY, and both 1-vote members will be SECONDARIES.
And if instead of 15 you give the same node only 2 votes - there will be NO PRIMARY after split, because no node can get the majority [of votes].
So users can think of additional votes for the server like they are just another mongod arbiter processes who share the same hardware with that server and vote altogether.
Also I think that we could benefit from adding these links (or at least some additional info from them) to the page:
http://openmymind.net/2012/1/7/Does-My-Replica-Set-Need-An-Arbiter/
http://www.kchodorow.com/blog/2012/01/04/replica-set-internals-bootcamp-part-i-elections/