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Zookeeper, mail # user - Ensure there is one master

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Ensure there is one master
ms209495 2013-11-26, 08:54

ZooKeeper is an excellent system but the problem with ensuring only one
master among clients bothers me.

Lets have a look at the situation when network partition happen: there is
part A (majority), and part B (minority).
Lets assume that before network partition happened the master was connected
to part B.
After the network partition, part A will elect new ZooKeeper leader, and
there will be new master elected among clients connected to part A.
At this time there are two masters - old in part B, and new in part A.
The only solution I can think about to this problem, is to ensure that the
new master is inactive for some time - to ensure that the old master in this
time will detect that it is not connected to ZooKeeper quorum, and will
deactivate itself as a master.
This solution assumes that timers on these machines work correctly.
Is it possible to ensure only one master using ZooKeeper without timing
assumptions ?


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Camille Fournier 2013-11-26, 20:10
ms209495 2013-11-26, 22:28
Cameron McKenzie 2013-11-26, 22:34
Alexander Shraer 2013-11-26, 22:58
Ted Dunning 2013-11-27, 00:53
Cameron McKenzie 2013-11-27, 00:57
Alexander Shraer 2013-11-27, 01:20
Ted Dunning 2013-11-28, 05:14
Maciej 2013-11-26, 23:17
Cameron McKenzie 2013-11-26, 23:41
Bryan Thompson 2013-11-26, 23:27
Ivan Kelly 2013-11-28, 18:04