When the threshold value for balancer is 0(zero) ,unexpected output is displayed --------------------------------------------------------------------------------
Key: HDFS-3286 URL: https://issues.apache.org/jira/browse/HDFS-3286 Project: Hadoop HDFS Issue Type: Bug Components: balancer Affects Versions: 0.23.0 Reporter: J.Andreina Fix For: 0.24.0 Replication factor =1 Step 1: Start NN,DN1.write 4 GB of data Step 2: Start DN2 Step 3: issue the balancer command(./hdfs balancer -threshold 0) The threshold parameter is a fraction in the range of (0%, 100%) with a default value of 10% When the above scenario is executed the Source DN and Target DN is choosen and the number of bytes to be moved from source to target DN is also calculated . Then the balancer is exiting with the following message "No block can be moved. Exiting..." which is not expected. {noformat} HOST-xx-xx-xx-xx:/home/Andreina/APril10/install/hadoop/namenode/bin # ./hdfs balancer -threshold 0 12/04/16 16:22:07 INFO balancer.Balancer: Using a threshold of 0.0 12/04/16 16:22:07 INFO balancer.Balancer: namenodes = [hdfs://HOST-xx-xx-xx-xx:9000] 12/04/16 16:22:07 INFO balancer.Balancer: p = Balancer.Parameters[BalancingPolicy.Node, threshold=0.0] Time Stamp Iteration# Bytes Already Moved Bytes Left To Move Bytes Being Moved 12/04/16 16:22:10 INFO net.NetworkTopology: Adding a new node: /default-rack/yy.yy.yy.yy:50176 12/04/16 16:22:10 INFO net.NetworkTopology: Adding a new node: /default-rack/xx.xx.xx.xx:50010 12/04/16 16:22:10 INFO balancer.Balancer: 1 over-utilized: [Source[xx.xx.xx.xx:50010, utilization=7.212458091389678]] 12/04/16 16:22:10 INFO balancer.Balancer: 1 underutilized: [BalancerDatanode[yy.yy.yy.yy:50176, utilization=4.650670324367203E-5]] 12/04/16 16:22:10 INFO balancer.Balancer: Need to move 1.77 GB to make the cluster balanced. No block can be moved. Exiting... Balancing took 5.142 seconds {noformat} -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira