[HDFS-14979] [Observer Node] Balancer should submit getBlocks to Observer Node when possible

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.3.0, 3.1.4, 3.2.2, 2.10.1
• Component/s: balancer & mover, hdfs
• Target Version/s: 2.10.1
• Assignee: Erik Krogen
• Reporter: Erik Krogen
• Created: 11/Nov/19 22:45
• Updated: 09/Dec/19 20:01
• Resolved: 13/Nov/19 20:10

Description

In HDFS-14162, we made it so that the Balancer could function when ObserverReadProxyProvider was in use. However, the Balancer would still read from the active NameNode, because getBlocks wasn't annotated as @ReadOnly. This task is to enable the Balancer to actually read from the Observer Node to alleviate load from the active NameNode.

Issue Links

• is related to: HDFS-14162 Balancer should work with ObserverNode
• is related to: HDFS-14973 Balancer getBlocks RPC dispersal does not function properly
• relates to: HDFS-15032 Balancer crashes when it fails to contact an unavailable NN via ObserverReadProxyProvider