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Date: Thu, 22 Sep 2011 22:16:59 +0530
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Subject: Re: zookeeper cluster spanning datacenters
From: Damu R <damu.devnull@gmail.com>
To: user@zookeeper.apache.org
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Hi Fourier,

We spread our ZKs across 3 data centers and in fact, these data centers are
> split across global regions (2 or 4 in one region, one in a remote region).
> To keep throughput up (and note that the throughput you have to worry about
> is only write throughput), we always ensure that the master is in one of the
> "local" data centers.
>
 How can we make sure the master (leader?) is in the local datacenter? Is
there any way we can control the leader election?


> If you have the machines to test, I would recommend running zk-smoketest  (
> https://github.com/phunt/zk-smoketest) on the proposed config.
>
This tool will be very useful to evaluate the setup.

Thanks
Damu

>
> C
>
> -----Original Message-----
> From: Damu R [mailto:damu.devnull@gmail.com]
> Sent: Thursday, September 22, 2011 10:50 AM
> To: user@zookeeper.apache.org
> Subject: zookeeper cluster spanning datacenters
>
> Hi,
> I would like to know the downsides of having a zookeeper cluster that spans
> multiple datacenters. The requirement is a datacenter failure should not
> bring down the zookeeper cluster. From my understanding it is not possible
> to have a hot/cold cluster kind of setup possible. So we are thinking of
> putting zk servers in 3 colos(1+1+1 or 2+2+3). One of the major drawback I
> could think of is the throughput of the system affected by latency. The
> system does not require high throughput and can accept some latency. How
> much effect will the latency have on the throughput of the system? What are
> the other downsides of spreading the cluster across datacenters?
>
> Regards
> Damu
>

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