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.
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