Hard disk drive components
- 1. Hard Disk Drive Components Basic components of a typical hard disk drives are: Disk Platters Read/ Write Heads Head Actuator mechanism Spindle motor Logic Board Cables and Connectors Configuration items (like jumpers, switches etc)
- 2. Typical hard disk drive components
- 3. Hard Disk Platters(Disks) Have one or more platters or disks 3 ½” are the most popular foe desktop computers 2 ½” and smaller are for notebooks and portable devices No. of platters is limited by its vertical physical size Maximum no. seen in 3 ½” drive is 12 But most have 6 or fewer
- 4. Originally made from aluminium/magnesium alloy Latter platters made of glass were made One such made by Dow corning corp. Called Memcor Composed of glass with ceramic implants, enabling it to resist cracking Offers great rigidity than metals Thermally stable than aluminium platters i.e (do not expand with changes in temperature )
- 5. • All modern drives use glass or glass- ceramic platters Fig: An example of a platter Platters
- 6. Recording Media All platters are covered with magnetically retentive substance called medium Three popular magnetic medium are: Oxide media Thin-film media AFC(anti-ferromagnetically coupled) media
- 7. Oxide Media Made up of various components, iron oxide as main Oxide coated platters are brownish or amber Since oxide medium are soft, it subjects to head crash damage Currently very few drives use oxide media
- 8. Thin-film Media It is thinner, harder and more perfect than oxide medium Also known as plated or sputtered media Platted media are created by depositing magnetic medium Sputtered media are created by 1. Coating platters with layer of nickel phosphorus 2. Applying cobalt alloy in complete vacuum deposition process
- 9. AFC Media Called anti ferromagnetically coupled media It consist of two magnetic layer separated by a thin 3-atom layer of element ruthenium IBM uses term “pixie dust” to refer this layer This AFC coupling causes the entire thickness to be the difference of top & bottom layer
- 10. IBM introduced AFC with 2 ½” Travelstar 30GN series notebook in 2001 In desktop 3 ½” drives started with Deskstar 120GXP Now used by Hitachi Global Storage Technologies AFC coated media looks like a mirror
- 11. Read / Write Heads Each platter ha two sets of read/write heads Set of read/write heads
- 12. When drive is at rest, heads are forced into direct contact with platters When spinning, air pressure develops below the head, lifts them off Distance b/w head & platter while spinning can be b/w 0.5 µ-in. to 5 µ-in