[HDFS-3619] isGoodBlockCandidate() in Balancer is not handling properly if replica factor >3

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.0.0, 2.0.0-alpha
• Component/s: balancer & mover
• Assignee: Junping Du
• Reporter: Junping Du
• Created: 09/Jul/12 15:46
• Updated: 28/Jul/15 00:43
• Resolved: 28/Jul/15 00:43

Description

Let's assume:
1. replica factor = 4
2. source node in rack 1 has 1st replica, 2nd and 3rd replica are in rack 2, 4th replica in rack3 and target node is in rack3.
So, It should be good for balancer to move replica from source node to target node but will return "false" in isGoodBlockCandidate(). I think we can fix it by simply making judgement that at least one replica node (other than source) is on the different rack of target node.

Issue Links

• is related to: HDFS-3495 Update Balancer to support new NetworkTopology with NodeGroup