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https://issues.apache.org/jira/browse/HDDS-16012?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shuo Huang reassigned HDDS-16012:
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Assignee: Shuo Huang
> SCM should flag closed-container replicas reporting equal BCSID with
> mismatched data checksums
> ----------------------------------------------------------------------------------------------
>
> Key: HDDS-16012
> URL: https://issues.apache.org/jira/browse/HDDS-16012
> Project: Apache Ozone
> Issue Type: Improvement
> Components: SCM
> Reporter: Ritesh Shukla
> Assignee: Shuo Huang
> Priority: Major
>
> h3. Problem
> Two replicas of a CLOSED container claiming the same BCSID assert the same
> committed content, so their container data checksums must match once both
> have reported trees. SCM already receives both {{sequenceId}} and
> {{dataChecksum}} in container replica reports, but nothing consumes
> {{dataChecksum}} in the replication path today. The BCSID-inflation bug class
> (HDDS-15542, HDDS-12986) produces exactly this signature -- equal sequenceId,
> different content -- and is invisible to datanode scanners because the
> inflated replica is internally consistent; only a cross-replica comparison
> can detect it.
> h3. Proposal
> A cheap comparison in SCM (or Recon) over data already reported:
> * For CLOSED containers where all replicas have reported non-empty data
> checksums: if any two replicas report equal {{sequenceId}} but different
> {{dataChecksum}}, emit a metric and a rate-limited WARN, and surface it in
> {{ozone admin container info}}.
> * No automated corrective action, consistent with the reconciliation design's
> System Safety principle; operators can run {{ozone admin container
> reconcile}}.
> h3. Constraints
> * Only compare when both replicas have reported checksums; suppress during
> known transient windows (tree not yet generated post-close/scan,
> mid-reconciliation) and debounce.
> * Persistent mismatch with equal BCSIDs after reconciliation indicates either
> BCSID inflation (a bug) or unrecoverable divergence -- both operator-worthy.
> * Equal checksums with unequal BCSIDs is NOT an anomaly (under-claiming is
> the safe direction); do not flag it.
> h3. References
> HDDS-10239, HDDS-15542, HDDS-12986, and the BCSID heuristics umbrella
> (HDDS-16011).
> Generated-by: Claude Code (Claude Fable 5)
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