[HDFS-9462] DiskBalancer: Add Scan Command

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.8.0
• Component/s: balancer & mover
• Assignee: Xiaobing Zhou
• Reporter: Xiaobing Zhou
• Created: 24/Nov/15 22:44
• Updated: 31/Oct/16 17:37
• Resolved: 31/Oct/16 17:37

Description

This is to propose being able to scan all the nodes that we send various plans to. In order to do the scan, scan command will talk to all involved data nodes through cluster interface(HDFS-9449) and data models(HDFS-9420) and compare the hash tag that it gets back to make sure that the plan is that we are interested in and print out the results.

As bonus, it should support the ability to print out the diff of what happened when a DiskBalancer run is complete. Assuming the state of the cluster is saved to file before.json. There should be two kinds of diffs:
1. Overall what happened in the cluster vs. before.json – just a summary
2. for a specific node – just like report command we should be able to pass in a node and as see the changes against the before.json

Issue Links

• is related to: HDFS-11038 DiskBalancer: support running multiple commands in single test