[HDFS-3411] Balancer fails to balance blocks between aboveAvgUtilized and belowAvgUtilized datanodes.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 0.23.0
• Component/s: balancer & mover
• Target Version/s: 2.0.0-alpha
• Assignee: Unassigned
• Reporter: Ashish Singhi
• Created: 12/May/12 15:12
• Updated: 28/Jul/15 00:39
• Resolved: 28/Jul/15 00:39

Description

Scaenario:
replication set to 1.
1. Start 1NN and IDN
2. pump 1GB of data.
3. Start one more DN
4. Run balancer with threshold 1.

Now DN1 is added into aboveAvgUtilizedDatanodes and DN2 into belowAvgUtilizedDatanodes. Hence overLoadedBytes and underLoadedBytes will be equal to 0. Resulting in bytesLeftToMove equal to 0. Thus balancer will exit without balancing the blocks.