Filesystem Recovery Tools and Tactics (Lesson Plan)

Definition

Filesystem recovery tools and tactics enable recovery of data otherwise lost to filesystem damage.

Objective

To mitigate data loss and recovery cost after master boot record or filesystem corruption.


Elements (generic to specific) (28 min)

Replacement from Source
  • Repair When Necessary
  • Preparation
  • Recovery
  • Cleanup
  • Snigglets
  • Summary (5 min)
  • Equipment

    Errors

    I'm too busy to make backups.

    Haste make waste. If you are too busy to make backups, you and your system are likely to be near overload. It is not merely imagination that "things always break at the worst possible time." FAA accident investigations find that catastrophe is nearly always the end of a "cascade sequence" or "chain of failure". Missing a periodic backup should ring alarm bells that cause you to look immediately for other problems and take corrective action.

    I didn't backup the master boot record, partition table, and/or boot sector.

    It may be possible to iteratively resconstruct the boot record using parted(8). Given partial information, like a range of cylinders, parted(8) can scan and detect filesystem signatures.

    grub(8) and lilo(8) can be reinstalled from most rescue systems.

    After your recover this time, make backups of your master boot record, superblocks, configuration, and content for all of your systems.

    I didn't backup the superblocks and group descriptors.

    ext2 and ext3 automatically copy all the group descriptors to the start of every group. Likewize the superblock is copied to the start of several groups.

    fsck.ext2 -s can use a copy of the superblock (and group descriptors).

    After your recover this time, make backups of your master boot record, superblocks, configuration, and content for all of your systems.

    Instructor Actions

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    Student Actions

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    Completion Standards