Known Issues in Streams Replication Manager
Learn about the known issues in Streams Replication Manager (SRM), the impact or changes to the functionality, and the workaround.
Known Issues
- 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.
- CDPD-11079: Blacklisted topics appear in the list of replicated topics
- If a topic was originally replicated but was later disallowed
(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 disallowed topic will be included in the response. Additionally, the disallowed 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. - CDPD-30275: SRM may automatically re-create deleted topics on target clusters
- If
auto.create.topics.enable
is enabled, deleted topics might get automatically re-created on target clusters. This is a timing issue. It only occurs if remote topics are deleted while the replication of the topic is still ongoing.
Limitations
- SRM cannot replicate Ranger authorization policies to or from Kafka clusters
- Due to a limitation in the Kafka-Ranger plugin, SRM cannot
replicate Ranger policies to or from clusters that are configured to use Ranger for
authorization. If you are using SRM to replicate data to or from a cluster that uses
Ranger, disable authorization policy synchronization in SRM. This can be achieved by
clearing the Sync Topic Acls Enabled
(
sync.topic.acls.enabled
) checkbox. - SRM cannot ensure the exactly-once semantics of transactional source topics
- SRM data replication uses at-least-once guarantees, and as a result cannot ensure the exactly-once semantics (EOS) of transactional topics in the backup/target cluster.
- SRM checkpointing is not supported for transactional source topics
- SRM does not correctly translate checkpoints (committed consumer group offsets) for transactional topics. Checkpointing assumes that the offset mapping function is always increasing, but with transactional source topics this is violated. Transactional topics have control messages in them, which take up an offset in the log, but they are never returned on the consumer API. This causes the mappings to decrease, causing issues in the checkpointing feature. As a result of this limitation, failover operations for transactional topics is not possible.