I don't think there is a straightforward answer to the question, but here is some insight.
If you use 3 servers with 3 data centers, you'll have one server per DC, which means that upon a crash, the clients in some data center will have to go remotely for reads. With 5 servers, at least one DC will have at most one server, which is a bit better, but the DC with one server will have the problem that with the one server crashing, the clients will need to go remotely for reads. 7 or 9 are better options, since you can have multiple nodes per DC to serve local read traffic. I have used 5-7 per DC with flexible quorums in a system I worked on. -Flavio > On 11 Aug 2015, at 08:47, Kaushal Shriyan <[email protected]> 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
