GSoC/GCI Archive
Google Code-in 2010 DragonFly BSD

Document Hammer recovery

completed by: gh0st

mentors: Justin Sherrill

DragonFly's filesystem, Hammer, keeps file history and data over time.  Deleted files can be recovered, or rolled back to earlier versions.

This task is to create a 'emergency guide' for someone on a Hammer filesystem who has lost data.  Document:

  • How to see what historical versions of a file exist
  • How to restore any one of those file versions
  • How to restore a directory, recursively
  • How to adjust the history retention for a Hammer filesystem.

Resources for this include the hammer(5) and hammer(8) man pages, and the DragonFly mailing list archives, where questions similar to this have been asked.

The best way to do this is to set up a DragonFly system and test it directly.

The results should be placed on a wiki page at