[HDFS-1332] When unable to place replicas, BlockPlacementPolicy should log reasons nodes were excluded

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.23.0
• Component/s: namenode
• Labels: newbie
• Hadoop Flags: Reviewed
• Assignee: Ted Yu
• Reporter: Todd Lipcon
• Created: 06/Aug/10 18:43
• Updated: 10/Aug/11 22:58
• Resolved: 18/May/11 01:27

Description

Whenever the block placement policy determines that a node is not a "good target" it could add the reason for exclusion to a list, and then when we log "Not able to place enough replicas" we could say why each node was refused. This would help new users who are having issues on pseudo-distributed (eg because their data dir is on /tmp and /tmp is full). Right now it's very difficult to figure out the issue.

Issue Links

• breaks: HDFS-2245 BlockManager.chooseTarget(..) throws NPE