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Ming Ma commented on HDFS-6425: ------------------------------- Sorry, the behavior was based on early version of hadoop. I just checked the trunk. It seems even after active is transitioned to standby, postponedMisreplicatedBlocks will reduce over time as DNs blockReport come in. Is it possible when a larger postponedMisreplicatedBlocks makes each blockReport takes longer time, it will make the cluster generate more over replica due to NN lock contention? > reset postponedMisreplicatedBlocks and postponedMisreplicatedBlocksCount when > NN becomes active > ----------------------------------------------------------------------------------------------- > > Key: HDFS-6425 > URL: https://issues.apache.org/jira/browse/HDFS-6425 > Project: Hadoop HDFS > Issue Type: Bug > Reporter: Ming Ma > Assignee: Ming Ma > Attachments: HDFS-6425.patch > > > Sometimes we have large number of over replicates when NN fails over. When > the new active NN took over, over replicated blocks will be put to > postponedMisreplicatedBlocks until all DNs for that block aren't stale > anymore. > We have a case where NNs flip flop. Before postponedMisreplicatedBlocks > became empty, NN fail over again and again. So postponedMisreplicatedBlocks > just kept increasing until the cluster is stable. > In addition, large postponedMisreplicatedBlocks could make > rescanPostponedMisreplicatedBlocks slow. rescanPostponedMisreplicatedBlocks > takes write lock. So it could slow down the block report processing. -- This message was sent by Atlassian JIRA (v6.2#6252)