Siyao Meng created HDDS-17127:
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             Summary: SCM retries checkpoint download from the leader without 
backoff
                 Key: HDDS-17127
                 URL: https://issues.apache.org/jira/browse/HDDS-17127
             Project: Apache Ozone
          Issue Type: Sub-task
          Components: SCM HA
            Reporter: Siyao Meng


When {{SCMStateMachine#notifyInstallSnapshotFromLeader}} fails to download the 
checkpoint, the future completes with null and Ratis sends the next install 
snapshot notification right away. There is no backoff and no limit, so a 
persistent failure turns into a tight loop. In the HDDS-16924 reproduction, two 
followers made ~12,000 download attempts in about 2 minutes, each logging two 
stack traces, and the leader logged an "Error streaming SCM DB checkpoint" 
stack trace for every one.

*Proposal:* back off between failed download attempts (e.g. exponential with a 
cap), keep one download in flight per follower, and rate-limit the error logs.



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