Vantage Data Recovery

Hard drive: noun – a mechanical device used in computers for storing and retrieving data, generally consisting of a spindle, motor, one or more disks, a corresponding number of read-write heads attached to an actuator, inside a case, with a circuit board attached.

Hard drive technology has evolved rapidly since the introduction of the Winchester drive in the 1960’s.  With ever-increasing size and speed has come new interfaces, magnetic coatings, data recording methods, etc., but the general mechanics have remained the same.

On the outside, a hard drive consists of a rigid aluminum case.  The case is not, as many people think, air tight.  It has filtered air vents for pressure equalization, and formed areas for the motor, disks and head assembly.  Attached to the case is a printed circuit board (PCB) that has power and data connectors.  This board provides the interface for the computer’s drive controller.  The various chips control the drive’s mechanical function and can contain the manufacturer’s settings for the drive (firmware).  The PCB also performs data buffering and caching, providing a smooth flow of data into and out of the drive.

Inside the drive are one or more disks or platters, mounted on the motor spindle.  The disks are generally made of aluminum, (although some drives have glass disks), and are coated with a magnetically retentive material.  Data is stored on either or both sides depending on the drive.  Multiple disks in a drive are stacked, separated by a thin spacer, on the motor spindle, and spin as a single unit.

Above and below each disk is a read/write head attached to an aerodynamic arm, which in turn is attached to the actuator mechanism, forming what is known as the head assembly.  When there is more than one disk (and therefore more than one pair of heads, they are attached as a group to the actuator, and move in unison.  In most hard drives, when the drive is powered off, the heads rest on the surface of the disks at a specified area (the landing zone).  Other hard drive manufacturers have developed a system where the heads actually park completely off the disks.  When the hard drive is powered up, the disks spin.  The movement of air across the surfaces created by spinning the disks lifts the heads to “fly” a microscopic distance off the surface.  The actuator controls the movement of the arms across the disks.

Data encoding is done in binary format.  Binary code is made up of ones and zeroes, or “off” and “on”.  To record data, the signal from the computer is channeled through the hard drive controller to the hard drive PCB which directs the actuator to move the heads to a specific point on the disk.  An electrical impulse is sent through the read/write head, which changes the magnetic polarity of that particular bit to represent the data.  When the command to read the data is sent, a basically similar process occurs in reverse. The actuator moves the heads to the area where the data is located, and reads the magnetic resistance, returning the information to be decoded.

Precision is a must.  Head flying height is measured in millionths of an inch as the actuator moves them from point to point, reading and writing data at lightning speed from disks spinning at 7200 RPM or greater.  Disk surfaces must be impeccably smooth to avoid crashes.  Head positioning must be incredibly accurate to read and write in the exact spot to maintain data integrity.  As drive capacities have increased and the physical size of the drives has decreased, tolerances have become tighter and tighter, requiring new, more precise technologies in both manufacturing and data recovery.

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