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Compatibility, Deprecation, and Migration Plan

For the message compatibility in the remote metadata topic, since the new fields are tagged fields, there will be no forward compatibility issue.

For the feature compatibility wise, the remote.log.metadata.compaction feature is disabled by default and can be enabled by upgrading the feature level using:

kafka-features.sh --bootstrap-server localhost:9092 \
  --upgrade remote.log.metadata.compaction=1

Once the feature level is upgraded, downgrading or disabling the feature is not supported. This is a forward-only change and clusters that enable the feature must remain at feature level 1 or higherThere is no backward compatibility issue for the Kafka clusters that have not run with the tiered storage mode, the new cluster can simply run with 2 new created metadata topics with the new code path.

For the clusters that already run in the tiered storage mode, the following migration plan will be executed prior to the broker’s bootstrap finishes to make sure the broker can execute the new code path.

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