[HDFS-15695] NN should not let the balancer run in safemode

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.3.1, 3.4.0, 3.2.3
• Component/s: namenode
• Labels: pull-request-available
• Assignee: Ahmed Hussein
• Reporter: Ahmed Hussein
• Created: 25/Nov/20 01:04
• Updated: 10/Jun/21 07:44
• Resolved: 02/Dec/20 21:35

Description

daryn reported that when the balancer moves a block, the target DN block reports the new location and hints to invalidate the source DN. The NN will not issue invalidations in safemode, so every moved block appears to be in excess. The data structures bloat and greatly increase the chance of a full GC.

The NN should refuse to provide block locations to the balancer while in safemode.

Issue Links

• links to: GitHub Pull Request #2489