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• Persist a BrokerRegistrationChange record, with the new list of online and offline log directories
• Update the Leader and ISR for all the replicas assigned to the failed log directories, using the existing replica state machinepersisting PartitionChangeRecords, in similar way to how leadership and ISR is updated when a broker becomes fenced, unregistered or shuts down.

Broker registration

Upon a broker registration request the controller will persist the broker registration as cluster metadata including the online and offline log directories for that broker. The controller may receive a new list of online and offline log directories — different from what was previously persisted in the cluster metadata for the requesting broker.

• If there are any missing log directories this means those have been removed from the broker’s configuration, so the controller will reassign all replicas currently assigned to the missing log directories to the remaining online log directories in the same broker.
• If there are new offline log directories, the controller will handle them as log directory failures, updating all leadership and ISR for partition with replicas on those offline log directories using the existing replica state machine, persisting new PartitionChangeRecords, in similar way to how leadership and ISR is updated when a broker becomes fenced, unregistered or shuts down.
• If the previous registration lists no log online directories the registration request is rejected unless it specifies a single online log directory. The controller will then assign all replicas in that broker to the specified log directory.

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