[KUDU-2688] LA rebalancer tries to amend non-fixable policy violations in case of RF=2 and three and more locations

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.8.0
• Fix Version/s: 1.9.0
• Component/s: CLI
• Code Review: http://gerrit.cloudera.org:8080/12375
• Assignee: Alexey Serbin
• Reporter: Alexey Serbin
• Created: 05/Feb/19 21:58
• Updated: 05/Feb/19 22:42
• Resolved: 05/Feb/19 22:42

Description

In case of RF=2 and more than two locations, the logic of the LA rebalancer suggests a fix for the distribution of replicas, and the rebalancer loops indefinitely trying to implement the suggested replica movements.

However, RF=2 is a special case: any replica distribution of a tablet with RF=2 is a violations of the placement policy constraints and it's impossible to fix that, regardless of number of locations in the cluster.