[HDFS-4861] BlockPlacementPolicyDefault does not consider decommissioning racks

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.23.7, 2.1.0-beta
• Component/s: namenode
• Labels: BB2015-05-TBR
• Assignee: Rushabh Shah
• Reporter: Kihwal Lee
• Created: 28/May/13 20:52
• Updated: 02/Dec/15 01:43

Description

getMaxNodesPerRack() calculates the max replicas/rack like this:

int maxNodesPerRack = (totalNumOfReplicas-1)/clusterMap.getNumOfRacks()+2;

Since this does not consider the racks that are being decommissioned and the decommissioning state is only checked later in isGoodTarget(), certain blocks are not replicated even when there are many racks and nodes.

Issue Links

• relates to: HDFS-9287 Block placement completely fails if too many nodes are decommissioning