data recovery software

About

When drives and storage media become unreadable by the usual methods, it is often possible to recover data using specialized software.

Damaged data generally falls into one of two categories, which we'll arbitrarily designate as "rescue" and "recovery":

• rescue: the directory listing can be read, and filesystem-checking utilities (such as scandisk in Microsoft Windows and fsck in Linux) report no errors, but attempting to read files results in error messages, time-outs, or bad data
• recovery: directory listings are unavailable or damaged

Different software is appropriate depending on which of the two situations is occurring. (All software listed is free/open-source unless otherwise indicated.)

rescue

Where directory listings are ok, but data in files cannot be read:

Linux

• ddrescue: like dd, but handles read errors better
• myrescue: similar to ddrescue, but tries to rescue readable stuff first

Self-booting

• SpinRite is an excellent tool for recovering damaged data on drives where the disk surface may be damaged but the drive hardware is usable. (Proprietary; ~$90; copyable)

Windows

• Stellar Phoenix Partition Recovery (Proprietary; ~$100)

recovery

Where directories bad, but raw data is readable:

Linux

• dares: for CDs/DVDs only; attempts to identify known file types; does not recover directory info
• testdisk: looks for munged partitions, lets you adjust partition table
  • PhotoRec is part of the testdisk package, and can extract files from raw data by looking for known headers. home page

Windows

• GetDataBack
• PC Inspector File Recovery (English)
• Smart PC Solutions: versions for FAT and NTFS; "freeware"/"free download"