Hi Kaushal,

As long as 2 DC are up and reachable you will be able to form a majority,
so it isn't very important whether you go with 3, 5, 7 or 9. However, it
does mean that if 1 DC is partitioned from the other 2, then anything
relying on zookeeper there will be stalled. I recommend you read
http://whilefalse.blogspot.com.es/2012/12/building-global-highly-available.html,
and consider if such a design would be suited to your usecase.

-Ivan

On Tue, Aug 11, 2015 at 9:47 AM Kaushal Shriyan <kaushalshriyan@gmail.com>
wrote:

> Hi,
>
> I have a very basic question of setting up Zookeeper ensemble across 3
> Datacenter. Since zookeeper quorum is based on odd number of nodes for
> Leader election. What would be the ideal odd number of nodes spread across
> 3 Datacenter is it 3 or 5 or 7 or 9? if either of DC1 or DC2 or DC3 is not
> reachable or degraded?
>
> DC1 meaning Datacenter 1
> DC2 meaning Datacenter 2
> DC3 meaning Datacenter 3
>
> Any help will be highly appreciable.
>
> Regards,
>
> Kaushal
>