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Diskless topics: Diskless topics store data exclusively in tiered storage, with no local log segments on brokers. Supporting mirroring for diskless topics requires adapting the fetch and replication mechanisms to work without local storage, which introduces changes to how mirror offsets are tracked and how truncation is handled during failover.

Source cluster throttling: The current replication throttling mechanism was designed for intra-cluster replica reassignment and may not be well suited for cross-cluster mirroring traffic. A dedicated throttling method would allow operators to control the bandwidth consumed by mirror fetch requests on the source cluster independently, preventing mirroring from competing with client traffic or internal replication without the limitations of repurposing the existing quota framework.

Test Plan

Unit Tests

Unit tests will cover individual component behavior:

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