It's a floor, yes. So for 3 you need 2, 5 needs 3, 7 needs 4 etc. On Tue, Aug 11, 2015 at 1:07 PM Kaushal Shriyan <[email protected]> wrote:
> Hi, > > While referring to > > http://whilefalse.blogspot.com.es/2012/12/building-global-highly-available.html > and the description "ZooKeeper requires a majority (n/2 + 1) of servers to > be available and able to communicate with each other in order to form a > quorum" I suppose it is floor function and not ceiling function while > referring to > https://en.wikipedia.org/wiki/Floor_and_ceiling_functions#Examples. Please > correct me if i am understanding it wrong? > > Regards, > > Kaushal > > On Tue, 11 Aug 2015 at 14:31 Flavio Junqueira <[email protected]> wrote: > > > 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 > > > > >
