How to retrieve data from an unknown partition

Written by chad anderson
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You can use a standard partition manager to rewrite an identical partition table after a partition has been lost or disk tools to attempt discovery of an unknown partition, but this isn't always a possibility. The better option might be TestDisk, a single cross-platform utility designed to recover missing or unknown partitions. TestDisk scans the entire disk and finds missing, old and unknown partitions that the program then can recover for you.

Skill level:


  1. 1

    Download and install TestDisk from the CGSecurity Website (see Resources). There are versions for near every operating system. If you already have a System Rescue CD or Hiren's Boot CD, TestDisk is included on those diagnostic tool sets.

  2. 2

    Launch a command prompt or terminal and type "testdisk" to start the application. Make sure you are running as the administrator or root user to run TestDisk, so, under UNIX-like systems, you should use the "su" command or prefix the "testdisk" command with "sudo" to operate as the root user. Under Windows, launch a command prompt by typing "cmd" into the Run dialogue. On other systems, simply click the terminal shortcut.

  3. 3

    Highlight your preferred logging option, then press "Enter" to begin with TestDisk. Use the arrow keys to select the hard drive where you wish to look for partitions, then press "Enter" to continue. Select the partition table type from the next page. TestDisk often will detect this automatically, but you should double-check to confirm.

  4. 4

    Highlight the "Analyze" option, then press "Enter" to begin the hard drive analysis. Press "Enter" to select "Quick Search" on the following page. Once Quick Search is complete, TestDisk will display any missing or unknown partitions. You can press the "p" key to view the files on them, then "q" to exit once you have browsed the file structure.

  5. 5

    Press "Enter" to continue to the final page. Highlight the "Write" option and press "Enter" to write the missing or unknown partitions to the disk. Exit TestDisk and reboot your system to be able to view the unknown partition's files.

Tips and warnings

  • If the "Quick Search" option does not find your missing or unknown partition, select the "Deeper Search" option from the Write menu to have TestDisk perform a more in-depth scan of your hard drive.

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