- When a drive fails or a file system becomes corrupt, the first approach usually involves a recovery attempt by a local technician. While this might seem to be a logical approach on the surface, it can often have devastating results. Data recovery is a specialized skill requiring specialized tools and specialized techniques to prevent further damage to the drive and/or file system.
The following describes operation that should NEVER be performed on a unhealthy drive or file system.
- Never Write to A Corrupt or Malfunctioning Drive – This is by far the most common mistake. Writing to a corrupt drive often destroys clues or “Rosetta Stones” that a qualified data recovery engineer uses to piece the file system back together. If you decide to attempt your own recovery, you must preform the recovery on a sector-by-sector copy of the drive.Note that this rule also applies to disk repair software, such as Norton Disk Doctor, ScanDisk, Rescue, or other repair software including tools indigenous to the operating system. Use of these utilities often butchers a corrupt file system to the point where very little (if any) data can be recovered.
- Never Subject a Malfunctioning Drive to Prolonged Operation – Avoid prolonged operation of an unhealthy drive; doing so could damage the media beyond recovery (See Acute Media Failure under Examples of Drive Damage). If a drive cannot be seen by the system BIOS or does not respond to low-level commands (i.e. you are unable to view the partition table or the system is unable to ID the drive during the boot sequence) then there is little chance of being able to recover the drive without specialized tools and skills.
- Never Open the Drive Enclosure – The drive enclosure should only be opened in a clean room. Tolerances in modern drives are extremely tight; track densities often exceed 4,000 tracks per inch and bit density often exceeds 70,000 bits per inch. To put these tolerances in perspective; the size of a bit is much smaller than the size of a biological cell (such as a skin cell), the physical size of a bit on the media is much closer to the size of a biological virus that infects a cell. With tolerances this tight, one dust spec can destroy hundreds of sectors or even trigger media failure (see Examples of Drive Damage). Furthermore, just loosening the cover screws can cause the drive to be knocked out of alignment to the point where the drive is no longer recognized by the drive’s control electronics (the circuit board on the drive).
- Performing any of the above operations will usually result in higher data recovery costs, and quite possibly reduce the amount of data that is recoverable.