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1. Stores the information of all live brokers.

   Code Block
   /brokers/ids/[broker_id] --> host:port (ephemeral; created by admin)

2. Stores for each partition, a list of the currently assigned replicas. For each replica, we store the id of the broker to which the replica is assigned. The first replica is the preferred replica. Note that for a given partition, there is at most 1 replica on a broker. Therefore, the broker id can be used as the replica id

   Code Block
   /brokers/topics/[topic]/[partition_id]/replicas --> {broker_id …} (created by admin)

3. Stores the id of the replica that’s the current leader of this partition

   Code Block
   /brokers/topics/[topic]/[partition_id]/leader --> broker_id (ephemeral) (created by leader)

4. Stores the id of the set of replicas that are in-sync with the leader

   Code Block
   /brokers/topics/[topic]/[partition_id]/ISR -->{broker_id, …}(created by leader)

5. This path is used when we want to reassign some partitions to a different set of brokers. For each partition to be reassigned, it stores a list of new replicas and their corresponding assigned brokers. This path is created by an administrative process and is automatically removed once the partition has been moved successfully

   Code Block
   /brokers/partitions_reassigned/[topic]/[partition_id] --> {broker_id …} (created by admin)

6. This path is used by the leader of a partition to enqueue state change requests to the follower replicas. The various state change requests include start replica, close replica, become follower. This path is created during the create topic admin command. This path is only deleted by the remove brokers admin command. The purpose of making this path persistent is to cleanly handle state changes like delete topic and reassign partitions even when a replica is temporarily unavailable (for example, being bounced).

   Code Block
   /brokers/topics/[topic]/[partition_id]/state/[broker_id] --> { state change requests ... } (created by admin)

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