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Or is it a cluster-level decision that a broker is no longer valid, in which case all affected partitions would immediately get replicated to new brokers as needed?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.
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.
Jun On Mon, Jul 22, 2013 at 2:14 AM, Jason Rosenberg <[EMAIL PROTECTED]> wrote:
Is the kafka-reassign-partitions tool something I can experiment with now (this will only be staging data, in the first go-round). How does it work? Do I manually have to specify each replica I want to move? This would be cumbersome, as I have on the order of 100's of topics....Or does the tool have the ability to specify all replicas on a particular broker? How can I easily check whether a partition has all its replicas in the ISR?
For some reason, I had thought there would be a default behavior, whereby a replica could automatically be declared dead after a configurable timeout period.
Re-assigning broker id's would not be ideal, since I have a scheme currently whereby broker id's are auto-generated, from a hostname/ip, etc. I could make it work, but it's not my preference to override that!
Jason On Mon, Jul 22, 2013 at 11:50 AM, Jun Rao <[EMAIL PROTECTED]> wrote:
Right now, we just have what's in the command line help.
Jun On Tue, Jul 23, 2013 at 8:19 AM, Jason Rosenberg <[EMAIL PROTECTED]> wrote:
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