[HDFS-6969] Archival Storage: INode#getStoragePolicyID should always return the latest storage policy

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Component/s: balancer & mover, namenode
• Hadoop Flags: Reviewed
• Assignee: Jing Zhao
• Reporter: Jing Zhao
• Created: 29/Aug/14 00:12
• Updated: 19/Sep/14 13:52
• Resolved: 02/Sep/14 00:56

Description

In general, every file should only provide exact one storage policy for the Mover, no matter its snapshot states. Suppose a file /foo/bar, and it is contained in snapshots s1 and s2 of the root. If /foo/bar, /.snapshot/s1/foo/bar and /.snapshot/s2/foo/bar have different storage policies, when running Mover, we have to select one of the storage policies, among which the latest one should be the best. And if /foo/bar is deleted, we should still use its storage policy before the deletion, since the file deletion should not trigger data migration.

Thus maybe what we can do is:
1. For a file with policy directly specified on it, alway follow the latest
2. Otherwise follow its latest parental path to identify its storage policy (simply following the parent link)