[HDFS-9127] Re-replication for files with enough replicas in single rack

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Invalid
• Assignee: Brahma Reddy Battula
• Reporter: Brahma Reddy Battula
• Created: 23/Sep/15 12:53
• Updated: 04/Dec/15 10:48
• Resolved: 04/Dec/15 10:48

Description

Found while debugging testcases in HDFS-8647

Scenario:
=======

Start a cluster with Single rack with three DN's
write a file with RF=3
adde two Nodes with different racks

As per blockplacement policy (Rack Awareness) atleast one replica needs to replicate to newly added rack.But it is not happening..Because of following reason.

when cluster was single rack,block will be removed from neededReplications after 3 replicas.

later, after adding new rack, only replications will happen which are present in neededReplications

So for the blocks which already have enough replicas, new rack replications will not take place..