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From Jordan Zimmerman <jor...@jordanzimmerman.com>
Subject Re: Zookeeper in two data centers and disaster recovery
Date Sat, 10 Dec 2016 18:42:50 GMT
The deployment-strategy-for-multi-data-centers was very interesting! Does any know where the
ZooNet code mentioned in the paper is? It would be nice to incorporate this into Curator.

-Jordan

> On Dec 8, 2016, at 8:05 PM, Michael Han <hanm@cloudera.com> wrote:
> 
> If "keep running" is defined as serving both read and write requests then
> no there is no way to build a reliable ZooKeeper ensemble across only two
> data centers simply because we can't guarantee that the single data center
> remaining after another one is lost contains the majority number of servers
> that can form a quorum. In this case you need at least 3 DC. If "keep
> running" is defined as serving only read requests then you could enable
> read only mode of ZK server so if a DC failed and remaining servers fail to
> form a quorum, your application can still read data out of ZK, but no write
> would be done after the point.
> 
> In general cross DC deployment design depends on your use case and trade
> offs you'd like to make. Similar topic was well discussed before [1], and
> there is a recent paper [2] which also provides good reference on this
> topic.
> 
> [1]
> http://zookeeper-user.578899.n2.nabble.com/zookeeper-deployment-strategy-for-multi-data-centers-td7582358.html#a7582364
> [2]
> https://www.usenix.org/system/files/conference/atc16/atc16_paper-lev-ari.pdf
> 
> On Thu, Dec 8, 2016 at 10:16 AM, Alvaro Gareppe <agareppe@gmail.com> wrote:
> 
>> I have Zookeeper running in a PRD environment with 3 instances running. 2
>> in 1 data center and 1 in other. But as zookeeper ensamble runs with a
>> majority if a loose the data center that runs 2 nodes of zookeeper, I loose
>> the cluster.
>> 
>> Is there any way to configure zookeeper (even adding more nodes is an
>> option) to keep running if some of the data center is offline (any one of
>> them). The only restiction, of course, is the number of datacenters
>> 
>> --
>> Ing. Alvaro Gareppe
>> agareppe@gmail.com
>> 
> 
> 
> 
> -- 
> Cheers
> Michael.


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