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From Flavio Junqueira <...@yahoo-inc.com>
Subject Re: Achieving quorum with only half of the nodes
Date Wed, 14 Jul 2010 20:52:34 GMT
Hi Sergei, I'm not sure what the implementation of QuorumVerifier you  
have in mind would look like to make your setting work. Even if you  
don't have partitions, variation in message delays can cause  
inconsistencies in your ZooKeeper cluster. Keep in mind that we make  
the assumption that quorums intersect.

-Flavio

On Jul 14, 2010, at 9:43 PM, Sergei Babovich wrote:

> Hi,
> We are currently evaluating use of ZK in our infrastructure. In our
> setup we have a set of servers running from two different power feeds.
> If one power feed goes away so does half of the servers. This makes
> problematic to configure ZK ensemble that would tolerate such outage.
> The network partitioning is not an issue in our case. The only  
> solution
> I come up with so far is to provide custom QuorumVerifier that will  
> add
> a little premium in case if all servers in the quorum set are from the
> same group. Basically if we have only half of votes but all of them
> belong to the same group then we decide to have a quorum.
> Any ideas or better solutions are very appreciated. Sorry if this has
> been already discussed/answered.
>
> Regards,
> Sergei
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flavio
junqueira

research scientist

fpj@yahoo-inc.com
direct +34 93-183-8828

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