[HDFS-5958] One very large node in a cluster prevents balancer from balancing data

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.2.0
• Component/s: balancer & mover

Environment

Hadoop cluster with 4 nodes: 3 with 500Gb drives and one with 4Tb drive.

• Assignee: Unassigned
• Reporter: Alexey Kovyrin
• Created: 17/Feb/14 02:26
• Updated: 04/Dec/15 00:50
• Resolved: 04/Dec/15 00:50

Description

In a cluster with a set of small nodes and one much larger node balancer always selects the large node as the target even though it already has a copy of each block in the cluster.

This causes the balancer to enter an infinite loop and stop balancing other nodes because each balancing iteration selects the same target and then could not find a single block to move.

Issue Links

• duplicates: HDFS-8826 Balancer may not move blocks efficiently in some cases