Page History

...

• As per KIP-866, a separate Controller quorum is setup first, and only then the existing brokers are reconfigured and upgraded.
• When configured for the migration and while still in ZK mode, brokers will:
  • update meta.properties to generate and include directory.id  and directory.ids
  • send BrokerRegistrationRequest including the log directory UUIDs
  • notify the controller of log directory failures via BrokerHeartbeatRequest
  • s
• During the migration, the active controller relies for accepts from brokers still in ZK mode, and relies on  to detect log directory failure notifications and still using , instead of monitoring ZK for notifications, but still uses full LeaderAndIsr  requests to process log directory failures for any brokers still running in ZK mode.
• The brokers restarting into KRaft mode for the first time update meta.properties to generate and include directory.id  and directory.ids  .
• During the migration, the active controller accepts broker registration requests from brokers restarting into KRaft mode, indicating multiple online log directories, but keeps brokers fenced until it learns of all partition to log directory assignments in that broker via the new AssignReplicasToDirs RPC.
• During the migration, replicas are assumed and assigned to log directory Uuid.ZERO until the actual log directory is learnt by the active controller from a broker running in KRaft mode.

...