[HDFS-3286] When the threshold value for balancer is 0(zero) ,unexpected output is displayed

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.23.0
• Fix Version/s: 2.0.0-alpha
• Component/s: balancer & mover
• Target Version/s: 2.0.0-alpha
• Hadoop Flags: Incompatible change, Reviewed
• Assignee: Ashish Singhi
• Reporter: J.Andreina
• Created: 17/Apr/12 15:59
• Updated: 28/Sep/15 20:58
• Resolved: 01/May/12 06:54

Description

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