junjie1233 opened a new pull request, #8616: URL: https://github.com/apache/hadoop/pull/8616
HDFS-17890: Avoid slow disks datanode when reading data. (Supersedes #8338, which was closed to reset the CI history that had accumulated flaky-test failures across trunk drift / runner load. The change is identical.) ## Change Deprioritize replicas on slow disks when returning block locations to clients, so reads prefer faster storage. Slow disks are detected via existing DataNode heartbeat reports and cached on the NameNode for efficient read-path lookup. - `dfs.namenode.deprioritize.slow.disk.datanode.for.read` (default `false`) gates the read-path reordering; the slow-disk cache rebuild only runs when the feature is enabled (zero overhead when disabled). - `dfs.namenode.slow.disk.cache.rebuild.interval` (default `30s`) controls cache rebuild cadence. - Stable sort preserves network-topology order for non-slow replicas; erasure-coded blocks are skipped. - Disk tracking is keyed on StorageID (`volumePath|storageID` format) for per-disk granularity. ## Tests `TestSlowDiskBlockLocations` (7 tests) covers cache rebuild, expiration, and read-path sorting. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
