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Tsz Wo Nicholas Sze commented on HDFS-8826: ------------------------------------------- The new patch only has minor changes javadoc. I will commit it without waiting for Jenkins. > Balancer may not move blocks efficiently in some cases > ------------------------------------------------------ > > Key: HDFS-8826 > URL: https://issues.apache.org/jira/browse/HDFS-8826 > Project: Hadoop HDFS > Issue Type: Sub-task > Components: balancer & mover > Reporter: Tsz Wo Nicholas Sze > Assignee: Tsz Wo Nicholas Sze > Attachments: h8826_20150811.patch, h8826_20150816.patch, > h8826_20150818.patch > > > Balancer is inefficient in the following case: > || Datanode || Utilization || Rack || > | D1 | 95% | A | > | D2 | 30% | B | > | D3, D4, D5 | 0% | B | > The average utilization is 25% so that D2 is within 10% threshold. However, > Balancer currently will first move blocks from D2 to D3, D4 and D5 since they > are under the same rack. Then, it will move blocks from D1. -- This message was sent by Atlassian JIRA (v6.3.4#6332)