HARD DISKS

INTRODUCTION TO HARD DISKS  Hard disk is the core fundamental component of the Computer system.  A mass storage device that stores the permanent data which can be retain as needed. e.g.Operating Systems,Programs and user files.  It is connected to the motherboard via ATA,SATA,SCSI cables and powered by the PSU.  It does not require the continuous power supply to retain the information.

HISTORY OF THE HARD DISKS  Information is the very important aspect in the term of the computer world and it need to be stored.  Initially, at the end of 18 Th century punch cards were used for the storage of information.  In 1953 IBM introduced the concept of the hard disk and the first commercial hard disk was introduced in  Initially were called as fixed disk,afterwards were called as Hard disk.  Name of the first hard disk was ‘Winchester’, which was of 3.75MB size only.

HISTORY OF THE HARD DISKS  First hard disk introduced by IBM was of size of two refrigerators. IBM 305,2 disks

HISTORY OF THE HARD DISKS GBytes Hard disk GBytes Hard disk 1.7Mbit/sq. 7.7Mbit/sq.

HISTORY OF THE HARD DISKS Gbytes GBytes 60Mbit/sq Mbit/sq

HISTORY OF THE HARD DISKS  Evolution of the hard disk is driven by the capacity and not by the performance.

BASICS OF THE HARD DISKS  A hard disk drive is a sealed unit that a PC uses for nonvolatile data storage.  A hard disk drive contains rigid, disk-shaped platters, usually constructed of aluminum or glass.  Hard disk uses the magnetic recording techniques, The information on a hard disk is stored in extremely small magnetic domains.  The capacity of hard disk is measured in MB,GB,TB,PB.  A modern desktop machine will have a hard disk with a capacity of gigabytes. Data is stored on the disk in the form of files.

ARCHITECTURE OF THE HARD DISK  Hard disk is made up of magnetic material coating.  It contains the platters,which are connected to the spindle  Platter is divided into concentric bands called tracks,tracks are further divided into sectors.  Sectors are grouped together to form cluster.  Multiple platters are arrange with help of the spindle to form a cylinder.

ARCHITECTURE OF THE HARD DISK  The basic physical construction of a hard disk drive consists of spinning disks with heads that move over the disks and store data in tracks and sectors.  The heads read and write data in concentric rings called tracks, which are divided up into segments called sectors, which normally store 512 bytes each.

ARCHITECTURE OF THE HARD DISK  For the read and write operation the head is used.  Usually each platters has a head for read write operation.  16 HEADS  8 PLATTERS

ARCHITECTURE OF THE HARD DISK EXPLORED INTERNAL HDD

ARCHITECTURE OF THE HARD DISK Platter Track Sector(512 bytes in DOS, 4 KB in NTFS)

TYPES OF THE HARD DISK  Hard drives are evolved based on the capacity.  They are most probably categorized based on capacity factor. Some of the Hard Disks:  ATA  FireWire  SCSI  RAID

TYPES OF THE HARD DISK ATA Disk DRIVES: Also known as IDE. It is of two types: 1)PATA: Parallel Advance Technology Attachment. These are installed internally. Uses pin wide ribbon cables to transfer data. We can connect two disk drives using PATA. 2)SATA: Serial Advance Technology Attachment. It has 7 pin data connection cable. Only one disk can be attached.

TYPES OF THE HARD DISK FireWire: It is used over low data rate operations. It lacks the performance of the ATA or SCSI e.g. no real time playback support SCSI: Small Computer System Interface Mostly used by Macintosh. It can connect 16 hard disks. Used in the servers. This is the hard drive which has the port used by SCSI cables.

TYPES OF THE HARD DISK RAID: REDUDENT ARRAY OF EXPENSIVE DISKS A Data storage virtualization technology which combines multiple hard drives in single logical unit for the data redundancy and performance improvement. Data is distributed into the drives in different levels called as RAID levels. e.g. RAID 0,RAID 1,RAID 2 etc. it Provides security with solid state drive without expenses of SSD system.

THINGS TO TAKE CARE OF THE HARD DISK  Physical Damage  Excessive Heat  File Fragmentation  Frequent ON-OFF  Power Surge

THE HARD DISK: LATEST UPDATES  There is lot much evolution in the hard disk. Currently HDD’s with capacity of 6-10 TB are used.  Starting from personal computers to the very big servers, very high capacity hard disks are used. Some of the Latest Updates: 1)Shingled Magnetic Recording It works by allowing tracks on the disk to overlap each other. It has 25% increase in the capacity.

THE HARD DISK: LATEST UPDATES 2)Two Dimensional Magnetic Recording: This HDD technology is necessary when tracks are so thin and close together. It has ability to get disk industry to 10 TB/sq. 3)Heat Assisted Magnetic Recording: It uses the drive with laser trapped to their heads,heating up the track just before the data is recorded

FUTURE OF THE HARD DISK  DNA HARD DRIVE: According to the paper published on Feb 18,2015 DNA Hard drives could be available for the storage soon. DNA HDD can store the data for the million of year.  60 TB HARD DISK could be the reality in 2016 Technology used : Heat Assisted Magnetic Recording

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