TestDisk

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TestDisk
TestDisk-logo.svg
Testdisk.png
Developer(s) Christophe Grenier
Stable release 6.14 / July 30, 2013 (2013-07-30)
Development status Active
Written in C
Platform Cross-platform
Type Data recovery
License GPL (free software)
Website www.cgsecurity.org/wiki/TestDisk

TestDisk is a free and open source data recovery utility. It is primarily designed to help recover lost data storage partitions and/or make non-booting disks bootable again when these symptoms are caused by faulty software, certain types of viruses or human error (such as accidentally erasing a partition table). TestDisk can be used to collect detailed information about a corrupted drive which can then be sent to a technician for further analysis.

Supported operating systems[edit]

TestDisk supports these operating systems:

Supported partition table type[edit]

TestDisk recognizes the following disk partitioning:

It also handles non-partitioned media.

Partition recovery[edit]

TestDisk queries the BIOS or the operating system in order to find the data storage devices (hard disks, memory cards, …) and their characteristics (LBA size and CHS geometry). TestDisk can[1]

TestDisk does a quick check of the disk's structure and compares it with the partition table for entry errors. Next, it searches for lost partitions[2][3] of these file systems:

However, it is up to the user to look over the list of possible partitions found by TestDisk and to select the one(s) which were being used just before the drive failed to boot or the partition(s) were lost. In some cases, especially after initiating a detailed search for lost partitions, TestDisk may show partition data which is simply from the remnants of a partition that had been deleted and overwritten long ago.

A step by step guide[4] explains how to use this software. TestDisk can be used in Computer forensics procedure,[5] it supports the EWF file format used by EnCase.

Filesystem repair[edit]

TestDisk can deal with some specific logical filesystem corruption:[6]

  • File Allocation Table, FAT[7]
    • FAT12 and FAT16
      • Find filesystem parameters to rewrite a valid boot sector
      • Use the two copies of the FAT to rewrite a coherent version
    • FAT32
      • Find filesystem parameters to rewrite a valid boot sector
      • Restore the boot sector using its backup
      • Use the two copies of the FAT to rewrite a coherent version
  • exFAT
    • Restore the boot sector using its backup
  • NTFS[8]
    • Find filesystem parameters to rewrite a valid boot sector
    • Restore the boot sector using its backup
    • Restore the Master File Table (MFT) from its backup
  • Extended file systems, ext2, ext3 and ext4
    • Find backup superblock location to assist fsck[9]
  • HFS+
    • Restore the boot sector using its backup

File recovery[edit]

When a file is deleted, the list of disk clusters occupied by the file is erased, marking those sectors available for use by other files created or modified thereafter. If the file wasn't fragmented and the clusters haven't been reused, TestDisk can recover the deleted file:

  • FAT file undelete[10]
  • NTFS file undelete[11]
  • exFAT file undelete
  • ext2 file undelete[12]

Popularity[edit]

TestDisk and PhotoRec (by the same author) have been downloaded more than 150,000 times in July 2008 from the primary website. In fact these utilities are even more popular as they can be found on various Linux Live CDs:

They are also packaged for numerous Linux distribution

See also[edit]

References[edit]

External links[edit]