Hello Neha, >>ZK cluster of 3 nodes will tolerate the loss of 1 node, but if there is a subsequent leader election for any reason, there is a chance that the cluster does not reach a quorum. It is less likely but still risky to some extent.
Does it mean if you have to tolerate 1 node loss without any issues, you need *at least* 4 nodes? On Tue, Jun 24, 2014 at 11:16 AM, Neha Narkhede <neha.narkh...@gmail.com> wrote: > Can you elaborate your notion of "smooth"? I thought if you have > replication factor=3 in this case, you should be able to tolerate loss > of a node? > > Yes, you should be able to tolerate the loss of a node but if controlled > shutdown is not enabled, the delay between loss of the old leader and > election of the new leader will be longer. > > So, you mean ZK cluster of 3 nodes can't tolerate 1 node loss? I've > seen many recommendations to run 3-nodes cluster, does it mean in > cluster of 3 you won't be able to operate after loosing 1 node? > > ZK cluster of 3 nodes will tolerate the loss of 1 node, but if there is a > subsequent leader election for any reason, there is a chance that the > cluster does not reach a quorum. It is less likely but still risky to some > extent. > > > On Tue, Jun 24, 2014 at 2:44 AM, Hemath Kumar <hksrckmur...@gmail.com> > wrote: > >> Yes kane i have the replication factor configured as 3 >> >> >> On Tue, Jun 24, 2014 at 2:42 AM, Kane Kane <kane.ist...@gmail.com> wrote: >> >> > Hello Neha, can you explain your statements: >> > >>Bringing one node down in a cluster will go smoothly only if your >> > replication factor is 1 and you enabled controlled shutdown on the >> brokers. >> > >> > Can you elaborate your notion of "smooth"? I thought if you have >> > replication factor=3 in this case, you should be able to tolerate loss >> > of a node? >> > >> > >>Also, bringing down 1 node our of a 3 node zookeeper cluster is risky, >> > since any subsequent leader election might not reach a quorum. >> > >> > So, you mean ZK cluster of 3 nodes can't tolerate 1 node loss? I've >> > seen many recommendations to run 3-nodes cluster, does it mean in >> > cluster of 3 you won't be able to operate after loosing 1 node? >> > >> > Thanks. >> > >> > On Mon, Jun 23, 2014 at 9:04 AM, Neha Narkhede <neha.narkh...@gmail.com> >> > wrote: >> > > Bringing one node down in a cluster will go smoothly only if your >> > > replication factor is 1 and you enabled controlled shutdown on the >> > brokers. >> > > Also, bringing down 1 node our of a 3 node zookeeper cluster is risky, >> > > since any subsequent leader election might not reach a quorum. Having >> > said >> > > that, a partition going offline shouldn't cause a consumer's offset to >> > > reset to an old value. How did you find out what the consumer's offset >> > was? >> > > Do you have your consumer's logs around? >> > > >> > > Thanks, >> > > Neha >> > > >> > > >> > > On Mon, Jun 23, 2014 at 12:28 AM, Hemath Kumar <hksrckmur...@gmail.com >> > >> > > wrote: >> > > >> > >> We have a 3 node cluster ( 3 kafka + 3 ZK nodes ) . Recently we came >> > across >> > >> a strange issue where we wanted to bring one of the node down from >> > cluster >> > >> ( 1 kafka + 1 zookeeper) for doing a maintenance . But the movement we >> > >> brought it to down on some of the topics ( only some partitions) >> > consumers >> > >> offset is reset some old value. >> > >> >> > >> Any reason why this is happened?. As of my knowledge when brought one >> > node >> > >> down its should work smoothly with out any impact. >> > >> >> > >> Thanks, >> > >> Murthy Chelankuri >> > >> >> > >>
