Components & Mechanism

People & Computers Hard Disk What purpose does it serve?

 Platters: The platters are the disks inside the drive where magnetized data is stored. Their numbers can vary depending on the size of the hard disk. These platters are mirror smooth and have high level tolerances.  Arm: Disk drive arm holds the read/write heads. The arm movement is extremely fast.

 Spindle and Spindle Motor: Platters of a hard disk are mounted to spindle.  Read/Write Heads: The read/write heads read and write data on the platters. The heads rest on the stationary platters when not in use. The spinning of platters creates air pressure that lifts the head off the platters. A small dust particle or even a fingerprint can be the reason for disk malfunction.

 The surface of a platter is logically divided into circular tracks, sectors and cylinders. Tracks are subdivided into sectors. The set of tracks that are at one arm position makes up a cylinder.  There is a thin layer of magnetic film on the platters. Magnetized data is stored on it in binary format (0 and 1). It is very much similar to floppy disk or tape.

 Disk speed consist of two parts: transfer rate and random access time also called positioning time.  Transfer rate is the rate at which data flows between the computer and the hard disk drive.  Random access time is the time required to move the disk arm to the desired cylinder  Rotational latency is the time required for a sector to rotate to disk head.

 There are many sophisticated hard drives available in the market, each designed for a specific application.  Hard Disk can vary in size but the idea of its mechanism is same.

Ahmad Abdallah Biren Patel