[HBASE-14110] Add CostFunction for balancing primary region replicas

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0, 1.3.0, 2.0.0
• Component/s: Balancer
• Hadoop Flags: Reviewed
• Assignee: Ted Yu
• Reporter: Ted Yu
• Created: 16/Jul/15 20:10
• Updated: 01/Jul/22 20:44
• Resolved: 17/Jul/15 16:58

Description

Currently replicas for the same region are spread across region servers.

However, one region server may serve disproportionately high number of primary region replicas. This has been observed in production cluster.

This issue adds PrimaryRegionCountSkewCostFunction which facilitates balancing primary region replicas evenly across region servers.

Thanks to Enis for fruitful discussion.