[HDFS-1351] Make it possible for BlockPlacementPolicy to return null

• Type: Test
• Status: Resolved
• Priority: Major
• Resolution: Invalid
• Affects Version/s: 0.22.0
• Component/s: namenode
• Assignee: Dmytro Molkov
• Reporter: Dmytro Molkov
• Created: 24/Aug/10 07:24
• Updated: 30/Aug/10 23:54
• Resolved: 30/Aug/10 23:54

Description

The idea is to modify FSNamesystem.chooseExcessReplicates code, so it can accept a null return from chooseReplicaToDelete which will indicate that NameNode should not be deleting extra replicas.

One possible usecase - if there are nodes being added to the cluster that might have corrupt replicas on them you do not want to delete other replicas until the block scanner finished scanning every block on the datanode.

This will require additional work on the implementation of the BlockPlacementPolicy, but with this JIRA I just wanted to create a basis for future improvements.