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From Patrick Hunt <>
Subject Re: zookeeper, how do you feed the pets?
Date Mon, 17 May 2010 07:02:11 GMT
Hi, ZK uses a quorum protocol (similar but not the same as paxos) for 
writes, as a result it's sensitive to inter-server latency. (however 
reads are always local and therefore not effected) Running a cluster 
fully w/in a colo you can achieve 15k writes/second, with a cluster 
distributed across a wan the write performance will be lower. You can 
see some detail on in-colo performance here and 



On 05/16/2010 07:10 PM, Chris Goffinet wrote:
> If you are running multiple datacenters, intend to have a lot of writes for counters,
I highly advise against it. We got rid of ZK because of that.
> -Chris
> On May 16, 2010, at 7:04 PM, S Ahmed wrote:
>> Can someone quickly go over how you go about using zookeeper if you want to store
counts and have those counts be accurate?
>> e.g. in digg's case I believe, they are using zookeeper so they can keep track of
digg's for a particular digg story.
>> Is it a backend change only and then storing API calls are uneffected?  is it a config
issue ?
>> What are the ramifications of using this addon, are writes slower because you have
to wait for the write to propogate to all the servers?

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