Known Issues in Streams Replication Manager

Learn about the known issues in Streams Replication Manager, the impact or changes to the functionality, and the workaround.

CDPD-22089: SRM does not sync re-created source topics until the offsets have caught up with target topic

Messages written to topics that were deleted and re-created are not replicated until the source topic reaches the same offset as the target topic. For example, if at the time of deletion and re-creation there are a 100 messages on the source and target clusters, new messages will only get replicated once the re-created source topic has 100 messages. This leads to messages being lost.

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CDPD-14019: SRM may automatically re-create deleted topics

If auto.create.topics.enable is enabled, deleted topics are automatically recreated on source clusters.

Prior to deletion, remove the topic from the topic whitelist with the srm-control tool. This prevents topics from being re-created.

srm-control topics --source [SOURCE_CLUSTER] --target [TARGET_CLUSTER] --remove [TOPIC1][TOPIC2]

SRM Cannot Replicate ACLs to or from Kafka Clusters that are Configured with Sentry.

When Sentry contains Kafka authorization policies for any ConsumerGroup resource, SRM cannot replicate authorization rules from one Kafka cluster to another in environments where Sentry is enabled. This is due to a Kafka resource conversion error in Sentry. For more information regarding the underlying Sentry issue, see SENTRY-2535 and the Kafka known issues in CDH Known Issues.

Disable authorization policy synchronization in SRM. This can be achieved by setting the sync.topic.acls.enabled property to false.

CDPD-13864 and CDPD-15327: Replication stops after the network configuration of a source or target cluster is changed

If the network configuration of a cluster which is taking part in a replication flow is changed, for example, port numbers are changed as a result of enabling or disabling TLS, SRM will not update its internal configuration even if SRM is reconfigured and restarted. From SRM’s perspective, it is the cluster identity that has changed. SRM cannot determine whether the new identity corresponds to the same cluster or not, only the owner or administrator of that cluster can know. In this case, SRM tries to use the last known configuration of that cluster which might not be valid, resulting in the halt of replication.

The internal topic storing the configuration of SRM can be deleted. After a restart SRM will re-create and re-populate it with the configuration data loaded from its property file. The topic is hosted on the target cluster of the replication flow. The topic name is: mm2-configs.[SOURCE_ALIAS].internal.

However, changing a replicated cluster's identity is generally not recommended.

CDPD-11709: Blacklisted topics appear in the list of replicated topics

If a topic was originally replicated but was later blacklisted, it will still appear as a replicated topic under the /remote-topics REST API endpoint. As a result, if a call is made to this endpoint, the blacklisted topic will be included in the response. Additionally, the blacklisted topic will also be visible in the SMM UI. However, it's Partitions and Consumer Groups will be 0, its Throughput, Replication Latency and Checkpoint Latency will show N/A.

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