[HDFS-9007] Fix HDFS Balancer to honor upgrade domain policy

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.8.0, 3.0.0-alpha1
• Assignee: Ming Ma
• Reporter: Ming Ma
• Created: 02/Sep/15 03:26
• Updated: 12/May/16 18:19
• Resolved: 04/Nov/15 18:23

Description

In the current design of HDFS Balancer, it doesn't use BlockPlacementPolicy used by namenode runtime. Instead, it has somewhat redundant code to make sure block allocation conforms with the rack policy.

When namenode uses upgrade domain based policy, we need to make sure that HDFS balancer doesn't move blocks in a way that could violate upgrade domain block placement policy.

In the longer term, we should consider how to make Balancer independent of the actual BlockPlacementPolicy as in HDFS-1431.