d1 3 understanding hard disk structure

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understanding hard disk strucutre basic


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Understanding hard disk structure : Understanding hard disk structure 1 INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM

Disk Platter::-- : Disk Platter::-- 2 INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM A hard disk has one or more platters - or disks - and each platter usually has a head on each of its sides. In modern drives the platters are made from glass or ceramic. The platters themselves are non-magnetic but have a magnetic coating which holds the magnetic impulses which represent the data. A typical hard drive will have three or four platters and modern varieties can hold 20GB per disk.

Read Write Head::-- : Read Write Head ::-- 3 INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM The read/write heads float on a cushion of air only nanometers above the surface of the platters. As the read/write heads pass over the spinning platters they magnetize the surface in a pattern which represents the data in digital form The distance between the read/write head and the surface of the hard drive(head fly/floating height) is so small that a strand of human hair will not pass between them.

Spindle motor::-- : Spindle motor ::-- 4 INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM The platters are mounted on the spindle which is turned by the drive motor. Most current hard disk drives spin at between 5,400 and 10,000 RPM.Modern hard drives can transfer 80 megabytes of data per second. The spindle motor must provide stable, reliable and consistent turning power for thousands of hours of often continuous use, to allow the hard disk to function properly

Head arm::-- : Head arm::-- 5 INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM The triangular-shaped head arm holds the read/write heads and is able to move the heads from the hub to the edge of the drive. There is one hard arm per read/write head and all of them are lined up and mounted to the actuator as a single unit. Head actuator ::-- The head arm is controlled by an actuator - which has to be incredibly accurate. 30,000 tracks can be stored within one inch of space on a platter. The hard disk's electronics control the movement of the actuator and the rotation of the disk, and perform reads and writes on demand from the disk controller via its interface to the computer

PowerPoint Presentation : 6 INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM Air filter  ::-- Hard drives are typically air-sealed to enable the heads to float and to avoid contamination from dust. The air inside the the hard drive enclosure is in constant motion and passes through the filter to remove any leftover contaminants from the manufacturing process and any particles or chemicals that may have somehow entered the enclosure.

PowerPoint Presentation : Tracks :-- circular area for data Platters are divided into concentric rings called tracks Sectors:-- Tracks are divide into wedge-shaped areas called sectors A sector typically holds 512 bytes of data INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM 7

Cylinder:-- : Cylinder:-- A cylinder is a three-dimensional concept consisting of all tracks in the same position vertically.. INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM 8

Cluster size in FAT& NTFS:-- : Cluster size in FAT& NTFS:-- INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM 9

CHS cylinder head sector addressing:-- : CHS cylinder head sector addressing:-- INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM 10

PowerPoint Presentation : Cylinder, head, sector (CHS) calculation 512 bytes per sector X sectors per track Y tracks per cylinder Number of bytes on a disk = Cylinders (tracks) x Heads (platters) x sectors First track is track 0 Each track is slightly different in size Inner tracks very small Out tracks relatively large INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM 11

Zoned bit recording (ZBR):-- : Zoned bit recording (ZBR):-- Group tracks by zone baseon distance from center of disk. Different zones contain different numbers of sectors More efficient use of tracks towards outside of platter INTERSOFT TECHNICAL INSTITUTE SURAT EMAIL--INTERSOFT@HOTMAIL.COM 12

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