THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
Controlled Shutdown
What does the tool do?
In 0.8, each partition can have multiple replicas. These replicas are distributed across different brokers for better availability. At any given instance of time, only one of these replicas will serve reads and writes. In other words, one replica acts as the leader. When a broker needs to be shutdown (A broker can be shutdown for doing a new release, changing config etc), it would be useful to still serve the requests for the partitions on this broker using the other in-sync replicas. It would be even more useful if this can be done seamlessly without the clients (producer and consumer) knowing about it. This is what the Controlled shutdown tool helps you to achieve. It transfers the leadership of the partitions from the broker (to be shutdown) to the other available replicas on the remaining brokers. A summary of the steps that the tool does is shown below -
1. Finds the jmx port of the broker where the controller resides.
2. Issues a shutdown command to the controller using the port specifying the broker to be shutdown.
3. The controller finds the list of partitions the broker is currently leading.
4. For each of the partitions, the controller finds another broker that is in the "in-sync" replica set and makes it the leader for the partition.
5. For a given partition, if the controller cannot find any other replica that is in the 'in-sync" set, it fails the shutdown.
6. The shutdown tool waits for the response of the controller. If it finds that the shutdown was not successful, it retries (this is configurable) and eventually succeeds or fails based on the controller response.