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From Camille Fournier <cami...@apache.org>
Subject Re: zookeeper deployment strategy for multi data centers
Date Fri, 03 Jun 2016 19:51:10 GMT
You could put the remaining available node in read-only mode. You could
reconfigure the cluster to have the majority nodes in the remaining data
center, but it would require reconfiguration and restart of the nodes in
the living data center. But there's no automatic fix for this, and if you
can safely override the quorum rule for your application perhaps you don't
need to use ZK at all?

On Fri, Jun 3, 2016 at 3:44 PM, Nomar Morado <j316services@icloud.com>
wrote:

> Thanks Shawn.
>
> Is there any settings to override the quorum rule? Would you know the
> rationale behind it?
>
> Ideally, you will want to operate the application even if at least one
> data center is up.
>
> Thanks.
>
>
> ÓĆáPrinting e-mails wastes valuable natural resources. Please don't print
> this message unless it is absolutely necessary. Thank you for thinking
> green!
>
> Sent from my iPhone
>
> > On Jun 3, 2016, at 9:05 AM, Shawn Heisey <apache@elyograg.org> wrote:
> >
> >> On 6/2/2016 4:06 PM, J316 Services wrote:
> >> We have two data centers and got two servers at each. At an event of a
> >> data center failure, with the quorum majority rule - the other
> >> surviving data center seems to be no use at all and we'll be out of
> luck.
> >
> > You are correct -- the scenario you've described is not fault tolerant.
> >
> > When setting up a geographically diverse zookeeper ensemble, there must
> > be at least three locations, so if there's a complete power or network
> > failure at one location, the other two can maintain quorum.  One
> > solution I saw discussed was a fifth tie-breaker server in a cloud
> > service like Amazon EC2, or you could go full-scale with two more
> > servers at a third datacenter.
> >
> > Thanks,
> > Shawn
> >
>

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