What is data recovery?

Well there are 3 types of recovery:
Logical Data Recovery - This type of recovery involves using software to recover deleted files, virus damage or damage to the operating system.
Non-Invasive Recovery - When the electronics on a drive fry for some reason or another and the hard drive doesn't have to go into the clean room, its non-invasive.
Invasive Data Recovery - If any of the interior parts fail, usually the heads, the drive has to be opened. Hard drives have to be opened in a clean room, if even the smallest speck of dust gets into the heads the platters can be damaged.

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When we get in a job wether it is a laptop drive or a multi-system RAID (Redundant Array of Individual Disks) the first thing we try to do is clone the hard drive sector by sector. If this works then it is a matter of using our software to return the data back in a way the user can work with it again.

If the drive won't clone then it is diagnosed to see if the problem is physical or electronic.

Here is answers.com's definition:

"data recovery Restoring data from disks, tapes, CDs and digital photo memory cards that have been damaged by accidents, natural disasters, power surges and malfunctioning electronics. Laptop hard disks are especially vulnerable if users are constantly on the move.

Several Techniques Organizations that specialize in retrieving data from damaged computers use a variety of techniques. They may be able to move the drive to a working computer, or they may have to open the drive and replace parts such as read/write heads, arms and chips. Sometimes, the platters are removed and placed into another drive.

It's Getting More Difficult
Newer disk drives are tested at the time of manufacture, and parameters unique to that drive are stored on the disk or in firmware. As the drive is used, data about bad sectors is added. If the drive is badly damaged in the areas that contain this drive information, replacing parts may not be enough to recover the data. Such drives require in-depth analysis for recovery.