HERE are some behind-the-scenes action in a typical data recovery lab:

Physical examination

When a damaged hard drive arrives at the lab, an engineer quickly inspects it for signs of physical damage. This step determines if the media needs to be fixed in a clean room. If fixing is required, the disk can't be powered up at all at this stage to avoid further damage.

If there are no broken parts to be replaced - and it is just a software corruption problem - the media will be sent to an image lab.

Clean room

In the Class 100 clean room (the number denotes the number of particles of size 0.5 ???m or larger permitted per cubic foot of air), an engineer in a clean suit opens up the entire drive to look at broken bits in detail (right).

A microscope is usually required for precision in singling out any mechanical defects. A multimeter, also known as a voltmeter, is commonly used for testing faulty electrical components.

The engineer then replaces the broken bits with spare parts that are in stock. He also updates the firmware, which may be specific to certain disk models. Without this update, the new parts may not work on the repaired drive.

If the drive was once soaked in liquid or mud, thorough cleaning may be needed to remove stains or dirt caked on it.

Image lab

The drive is then powered up, followed by a sector-by-sector copying of its contents to the rescue company's own servers.

A software engineer then builds an image by piecing together the sectors copied. This is done by examining the data patterns and extrapolating from the parts of the copied sectors that are not damaged. Proprietary tools are involved at this stage and the process is also the most well-guarded trade secret in the data recovery industry.

From the image, file names and file structures are extracted.

Collection

The copied data is then delivered to customers in a DVD or another hard drive. The whole process could take a few hours to weeks or months. Any delay is usually due to missing spare parts and firmware. The severity of damage also determines how long the rescue work takes.

This story was first published in The Straits Times Digital Life on 27 May 2008.