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Stephen O'Donnell commented on HDFS-16093: ------------------------------------------ I'm not sure it we can simply removed them. There is also a distinction between DECOMMISSIONING and DECOMMISSIONED. It is possible for all 3 replicas of a file to be on DECOMMISSIONING host, and therefore it can only be read if those hosts are returned. For DECOMMISSIONED hosts which are alive and not stale, I think they can be used for reads in some circumstances. I recall seeing some comments in the code suggesting DECOMMISSIONED replicas can be used as a "last resort". > DataNodes under decommission will still be returned to the client via > getLocatedBlocks, so the client may request decommissioning datanodes to read > which will cause badly competation on disk IO. > -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- > > Key: HDFS-16093 > URL: https://issues.apache.org/jira/browse/HDFS-16093 > Project: Hadoop HDFS > Issue Type: Improvement > Affects Versions: 3.3.1 > Reporter: Daniel Ma > Priority: Critical > > DataNodes under decommission will still be returned to the client via > getLocatedBlocks, so the client may request decommissioning datanodes to read > which will cause badly competation on disk IO. > Therefore, datanodes under decommission should be removed from the return > list of getLocatedBlocks api. > !image-2021-06-29-10-50-44-739.png! -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org