The document provides information about hard disk drives, including:
- Hard disk drives store digitally encoded data on rapidly rotating platters with magnetic surfaces. Data is stored as binary 0s and 1s.
- Disk structures include tracks, sectors, cylinders, and clusters. Tracks are circular areas on disks, sectors are the smallest storage units, cylinders group same tracks, and clusters are groups of sectors.
- Performance is measured by latency, data rate, and seek time. Latency depends on rotation speed, data rate is bytes/second, and seek time is retrieving requested data.
- Common interfaces are IDE, SATA, and SCSI, which have different connectors and data transfer speeds.
3. Introduction
TITLE: HARD DISK DRIVE
CLASS: MASTER COMPUTER SCIENCE (MCS)
SUBJECT: OPERATING SYSTEM
PRESENT BY ZUBAIR FAROOQ
DATE 20 AUGUST, 2015
4. Hard Disk
A hard disk drive is a non-
volatile storage device that
stores digitally encoded data
on rapidly rotating platters with
magnetic surface.
Its stored in 0 (or) 1.
The hard disk drive was
originally invented by an IBM
team led by Rey Johnson in
1956.
6. Disk structures
Tracks-
circular areas of the disk
Data first written to outer most track
Over 1000 on a hard disk
Sectors-
Divides tracks sections
Sectors are the smallest physical storage units on a disk-
Each sector stores 512 bytes of data
Cylinders-
Logical groupings of the same track on each disk surface in a disk
unit
Track create cylinder inside the hard disk.
Clusters (Blocks) -
Groups of sectors used by operating system
64 sectors in one cluster
7. Disk / Platter
Each platter has 2 surfaces
Platter is made from aluminum, ceramic, or class,
coated with a magnetic materials such as iron oxide.
Platter spin between 4,800 to 15,000 round per
minute(RPM)
Platter contain number of tracks and sectors.
8. Performance characteristics
There are three ways to measure the
performance of a hard disk:
Latency
Latency is the delay for the rotation of the
disk to bring the require disk sector under the
read-write mechanism.
It depends on rotational speed of a disk,
measured in revolutions per minute (rpm).
9. Performance characteristics
Data rate
The data rate is the number of bytes per second that the drive can
deliver to the CPU. Rates between 5 and 40 megabytes per second are
common.
Seek time
The seek time is the amount of time between when the CPU requests
a file and when the first byte of the file is sent to the CPU. Times between
10 and 20 milliseconds are common
10. Hard Drive Interfaces Overview
IDE (integrated drive electronics)
SATA (Serial Advanced Technology Attachment)
SCSI (small computer system interface)
11. IDE (Integrated Device Electronics)
1. It has a 40 pin connector.
2. Data transfer rate is 133MB/s.
3 .When installed this type of hard drives ensure that the jumpers are
correctly configured.
Also known ATA (Advance Technology Attachment)
12. SATA (Serial Advanced Technology
Attachment)
It has a 7 pin connector.
It is the latest high-speed type of hard drive connectors.
Data transfer rate is 300Mb/s.
13. SCSI (Small Computer System Interface)
1. It has a 50 or 68 pin connector.
2. The data transfer rate is 600Mb/s .