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From Neha Narkhede <neha.narkh...@gmail.com>
Subject Re: Consumer offset is getting reset back to some old value automatically
Date Tue, 24 Jun 2014 18:16:01 GMT
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 <hksrckmurthy@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.isturm@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.narkhede@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 <hksrckmurthy@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
> > >>
> >
>

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