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Kafka, mail # user - Replacing brokers in a cluster (0.8)


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Re: Replacing brokers in a cluster (0.8)
Jun Rao 2013-07-22, 15:51
A replica's data won't be automatically moved to another broker where there
are failures. This is because we don't know if the failure is transient or
permanent. The right tool to use is the kafka-reassign-partitions tool. It
hasn't been thoroughly tested tough. We hope to harden it in the final
0.8.0 release.

You can also replace a broker with a new server by keeping the same broker
id. When the new server starts up, it will replica data from the leader.
You know the data is fully replicated when both replicas are in ISR.

Thanks,

Jun
On Mon, Jul 22, 2013 at 2:14 AM, Jason Rosenberg <[EMAIL PROTECTED]> wrote:

> I'm planning to upgrade a 0.8 cluster from 2 old nodes, to 3 new ones
> (better hardware).  I'm using a replication factor of 2.
>
> I'm thinking the plan should be to spin up the 3 new nodes, and operate as
> a 5 node cluster for a while.  Then first remove 1 of the old nodes, and
> wait for the partitions on the removed node to get replicated to the other
> nodes.  Then, do the same for the other old node.
>
> Does this sound sensible?
>
> How does the cluster decide when to re-replicate partitions that are on a
> node that is no longer available?  Does it only happen if/when new messages
> arrive for that partition?  Is it on a partition by partition basis?
>
> Or is it a cluster-level decision that a broker is no longer valid, in
> which case all affected partitions would immediately get replicated to new
> brokers as needed?
>
> I'm just wondering how I will know when it will be safe to take down my
> second old node, after the first one is removed, etc.
>
> Thanks,
>
> Jason
>