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Zookeeper, mail # dev - quorum of 4 servers


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quorum of 4 servers
Ted Yu 2012-07-20, 21:05
Hi,
I want to get people's opinion on the following statements:

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While zk nodes are out of service (e.g. OS upgrade), it should be OK to
have an even number of nodes.

For zk or any other kind of voting system, it is misleading to focus on
having an odd number of voters to avoid a tie vote.  The real focus should
be "I want to tolerate at least N wrong or missing votes, so I need to have
N + (N+1 or MORE) voters to make sure that N wrong or missing votes will
not kill my service."  Typically people just build out (N + N+1) which
means you are always starting with an odd number of voters.
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Cheers