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Zookeeper >> mail # user >> Ensuring there is at most one master


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Re: Ensuring there is at most one master
>> At this time there are two masters - old in part B, and new in part A.

After the network partition, there shouldn't be a leader in part B since it
is a minority and will not be able to form a quorum.

Thanks,
Neha
On Tue, Nov 26, 2013 at 6:34 AM, Maciej Smoleński <[EMAIL PROTECTED]> wrote:

> Hi,
>
> ZooKeeper is an excellent system. 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 ?
>
> Thanks,
> Maciej
>