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https://issues.apache.org/jira/browse/KAFKA-20022?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shubham Raj updated KAFKA-20022:
--------------------------------
Priority: Critical (was: Blocker)
> Kafka Dual Write Mode Sync Failure
> ----------------------------------
>
> Key: KAFKA-20022
> URL: https://issues.apache.org/jira/browse/KAFKA-20022
> Project: Kafka
> Issue Type: Bug
> Components: controller
> Affects Versions: 3.9.0
> Reporter: Shubham Raj
> Assignee: David Arthur
> Priority: Critical
>
> Hi,
> We migrated our Kafka cluster (v3.9) to *dual write mode* three weeks ago as
> part of the planned one-month transition away from ZooKeeper. Recently, the
> controller sync between the ZooKeeper and KRaft metadata went out of
> alignment. As a result, the cluster is no longer in dual write mode. As
> proposed in KAFKA-16171, attempts to restart the controllers did not restore
> sync, and the ZooKeeper metadata is now lagging behind as per logs.
> *Impact*
> * Dual write mode is no longer active, increasing risk of metadata
> divergence.
> * ZooKeeper metadata is stale compared to KRaft.
> * Migration timeline is at risk.
> *Repetitive Logs in leader controller:*
> {code:java}
> [2025-12-29 01:44:23,852] ERROR Encountered zk migration fault: Unhandled
> error in SyncKRaftMetadataEvent
> (org.apache.kafka.server.fault.LoggingFaultHandler)
> java.lang.RuntimeException: Check op on KRaft Migration ZNode failed. Sent
> zkVersion = 5349155. This indicates that another KRaft controller is making
> writes to ZooKeeper.
> at
> kafka.zk.KafkaZkClient.handleUnwrappedMigrationResult$1(KafkaZkClient.scala:2050)
> at
> kafka.zk.KafkaZkClient.unwrapMigrationResponse$1(KafkaZkClient.scala:2076)
> at
> kafka.zk.KafkaZkClient.$anonfun$retryMigrationRequestsUntilConnected$2(KafkaZkClient.scala:2101)
> at
> scala.collection.StrictOptimizedIterableOps.map(StrictOptimizedIterableOps.scala:100)
> at
> scala.collection.StrictOptimizedIterableOps.map$(StrictOptimizedIterableOps.scala:87)
> at scala.collection.mutable.ArrayBuffer.map(ArrayBuffer.scala:42)
> at
> kafka.zk.KafkaZkClient.retryMigrationRequestsUntilConnected(KafkaZkClient.scala:2101)
> at
> kafka.zk.migration.ZkTopicMigrationClient.$anonfun$createTopic$1(ZkTopicMigrationClient.scala:137)
> at
> kafka.zk.migration.ZkTopicMigrationClient.createTopic(ZkTopicMigrationClient.scala:111)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationZkWriter.lambda$null$3(KRaftMigrationZkWriter.java:233)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationDriver.applyMigrationOperation(KRaftMigrationDriver.java:246)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationDriver.applyMigrationOperation(KRaftMigrationDriver.java:240)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationDriver.access$300(KRaftMigrationDriver.java:63)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationDriver$SyncKRaftMetadataEvent.lambda$run$0(KRaftMigrationDriver.java:844)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationDriver.lambda$countingOperationConsumer$6(KRaftMigrationDriver.java:970)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationZkWriter.lambda$handleTopicsSnapshot$4(KRaftMigrationZkWriter.java:230)
> at java.base/java.lang.Iterable.forEach(Iterable.java:75)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationZkWriter.handleTopicsSnapshot(KRaftMigrationZkWriter.java:228)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationZkWriter.handleSnapshot(KRaftMigrationZkWriter.java:96)
> at
> org.apache.kafka.metadata.migration.KRaftMigrationDriver$SyncKRaftMetadataEvent.run(KRaftMigrationDriver.java:843)
> at
> org.apache.kafka.queue.KafkaEventQueue$EventContext.run(KafkaEventQueue.java:132)
> at
> org.apache.kafka.queue.KafkaEventQueue$EventHandler.handleEvents(KafkaEventQueue.java:215)
> at
> org.apache.kafka.queue.KafkaEventQueue$EventHandler.run(KafkaEventQueue.java:186)
> at java.base/java.lang.Thread.run(Thread.java:840)
> [2025-12-29 01:44:23,852] TRACE [KRaftMigrationDriver id=10002] Received
> metadata delta, but the controller is not in dual-write mode. Ignoring this
> metadata update. (org.apache.kafka.metadata.migration.KRaftMigrationDriver)
> [2025-12-29 01:44:23,852] TRACE [KRaftMigrationDriver id=10002] Received
> metadata delta, but the controller is not in dual-write mode. Ignoring this
> metadata update. (org.apache.kafka.metadata.migration.KRaftMigrationDriver)
> [2025-12-29 01:44:23,852] TRACE [KRaftMigrationDriver id=10002] Received
> metadata delta, but the controller is not in dual-write mode. Ignoring this
> metadata update. (org.apache.kafka.metadata.migration.KRaftMigrationDriver)
> [2025-12-29 01:44:23,852] TRACE [KRaftMigrationDriver id=10002] Received
> metadata delta, but the controller is not in dual-write mode. Ignoring this
> metadata update. (org.apache.kafka.metadata.migration.KRaftMigrationDriver)
> [2025-12-29 01:44:23,852] TRACE [KRaftMigrationDriver id=10002] Received
> metadata delta, but the controller is not in dual-write mode. Ignoring this
> metadata update. (org.apache.kafka.metadata.migration.KRaftMigrationDriver)
> {code}
>
>
> *cluster status*
> {code:java}
> ClusterId: QBC8K1kNS02Sl9930_QDAA
> LeaderId: 10002
> LeaderEpoch: 253
> HighWatermark: 12515984
> MaxFollowerLag: 0
> MaxFollowerLagTimeMs: 111
> CurrentVoters: [10001,10002,10003]
> CurrentObservers:
> [5,4,1104,6,3,1,1103,1112,1108,1107,1109,1101,1102,2,1106,1110,1111,1105]
> {code}
>
> *Migration data in zookeeper*
> {code:java}
> In [4]: zk_client.get('/kafka/qa/migration')
> Out[4]:
> (b'{"version":0,"kraft_metadata_offset":10840503,"kraft_controller_id":10002,"kraft_metadata_epoch":170,"kraft_controller_epoch":253}',
> ZnodeStat(czxid=7129652820618, mzxid=7176892421062, ctime=1765176701970,
> mtime=1766986727917, version=5349156, cversion=0, aversion=0,
> ephemeralOwner=0, dataLength=130, numChildren=0, pzxid=7129652820618))
> {code}
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