[HDFS-1793] Add code to inspect a storage directory with txid-based filenames

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Edit log branch (HDFS-1073)
• Fix Version/s: Edit log branch (HDFS-1073)
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 29/Mar/11 07:01
• Updated: 07/Jul/11 05:56
• Resolved: 01/Apr/11 03:46

Description

After HDFS-1538, the startup of the NN is done with the following phases:

• Inspect storage directories
• Formulate a "load plan", where a load plan is:
  • A set of recovery actions (eg deleting half-uploaded checkpoint uplods)
  • The fsimage to restore
  • A sequence of edit logs to replay
• Run the recovery
• Load specified image
• Load specified edits.

This JIRA adds code to inspect a set of storage directories where the image and edits files are named according to the scheme designed in HDFS-1073, and formulate such a load plan.