disk drives

Introduction To Disk Drives

By

Ammar Tahir, Nofal Ejaz, Taha Fayyaz, Muhammad Mohsin Khan,

Haroon Siddique12F-8098, 12F-8014, 12F8006

12F-823912F-8235

FAST-NUSeptember 12, 2012

A device that allows a computer to read from and write data to computer discs.

What is disk drive?

Optical Disk DrivesA form of disk drives that

uses laser beams to read and write data on shinny

plastic discs.

Magnetic Disk DrivesA form of disk drives that

uses magnetization

processes to read and write data on shinny metallic discs.

Types of disk drives

Optical Disc Drives

Compact Disc◦ Uses red laser beam

Digital Video Disc◦ Uses red laser beam

Blu-ray◦ Uses blue laser beam

Types of Optical Disk Drives

CD-ROM◦ 700 Mbytes Read Only Data

CD-R◦ 700 Mbytes of Recordable Data

CD-RW◦ 700 Mbytes of Rewritable Data

Compact Discs

DVD-ROM◦ ~4.7 Gbytes of Read Only Data

DVD-R◦ ~4.7 Gbytes of Recordable Data

DVD-R DL◦ ~8.5 Gbytes of Read Only Data in Dual Layers

DVD-RW◦ ~4.7 Gbytes of Rewriteable Data

DVD-RW DL◦ ~8.5 Gbytes of Rewriteable Data in Dual Layers

Digital Video Discs

BD-ROM◦ 25 Gbytes of Read Only Data

BD-R◦ 25 Gbytes of Recordable Data

BD-R DL◦ 50 Gbytes of Recordable Data in Dual Layers

BD-RW◦ 25 Gbytes of Rewriteable Data

BD-RW DL◦ 50 Gbytes of Rewriteable Data in Dual Layers

Blu-ray Discs

Magnetic Disc Drives

Floppy DriveIt is composed of a disk of thin,flexible metallic coated storage mediumencased in a rectangular plastic shell

Hard DriveMain storage device which usesrotating metallic media and magneticrecoding systems to process and storedigital data encased in a metallic box.

Types of Magnetic Disk Drives

8 inch Floppy Drive

5.25 inch Floppy Drive

3.5 inch Floppy Drive

Floppy Disc Drives

ATA (Advanced Technology Attachment)

◦ Also know as IDE/PATA.◦ Offers up to 16~133 MB/sec transfer rate.◦ It sends 8 bit data at a time◦ ATA cables are use to

connect them.◦ Usually have 40 pins.

Hard Disk Drive

SATA (Serial ATA)

◦ Usually have 7 pins. 3 pins grounded and 4 pins for sending and receiving.

◦ Offers up to 300MB/sec transfer rate.

◦ It sends data bit by bit.◦ SATA Cables are used to

connect SATA HDD.

Hard Disk Drive

SCSI (Small Computer System Interface)

◦ Usually have 50 to 68 pins.◦ Offers up to 640MB/sec

transfer rate.◦ This drives are hot

swappable.◦ SCSI cables are used to

connect SCSI HDD. Maximum of 16 drives can be connected in a single SCSI cable.

Hard Disk Drive

SAS (Serial Attached SCSI)

◦ SAS Drives generally offers 805 MB/sec transfer rate.

◦ This drives are hot swappable.

◦ SAS Cables are used to connect SAS Drives.

◦ Maximum of 128 drives can be connected in a single sas cable.

Hard Disk Drive

How Magnetic Storage WorksWrite head

StorageMedium

Random particles(no data stored)

Current flow(write operation)

Organized particles(represent data)

As the mediumrotates, the headwrites the data.

Before a magnetic disk can be used, it must be formatted—

a process that maps the disk's surface and determines how

data will be stored.

During formatting, the drive creates circular tracks around

the disk's surface, then divides each track into sectors.

Formatting.

Formatted Disk

An optical drive uses reflected light to read data.

To store data, the disk's metal surface is covered

with tiny dents (pits) and flat spots (lands), which

cause light to be reflected differently.

When an optical drive shines light into a pit, the

light cannot be reflected back. This represents a bit

value of 0 (off). A land reflects light back to its

source, representing a bit value of 1 (on).

How Optical Storage Works

How Optical Storage Works

01

The End