A Presentation on Hard Disks

By: Team 4 (HIS44):(1)Samarjyoti Das (972151)(2)Subhadeep Ghosh (986570)(3)Dipanjan Das (986510)(4)Sudhamayee Pradhan (976267)(5)Ankita Mishra (976310)

Contents•WHAT HARD DISK IS?•COMPONENTS OF HDD•WHY HARD DISK IS USED?•DETAILS ABOUT FUNCTIONALITIES•HARD DISK MECHANISM•PERFORMANCE CHARACTERISTICS•THINGS TO BE TAKEN CARE OF•DEPENDENCIES•LATEST MARKET UPDATES•COMPARISON BETWEEN SSD AND HDD•ADVANCE TECHNOLOGY UPDATES

What Hard Disk is ?

•Secondary storage device

•Also called Disk drives or hard drives or HDD

•Hard describes anything that is permanent or physically exists

•It is a non volatile form of storage

Components

Why Hard Disk is used?•Used to store and provide relatively quick and random access to large amounts of data (in Gbs or Tbs)•Data is stored permanently•If a computer's CPU is the brain of the PC, the HDD is its long-term memory-which preserves data, programs and the OS even while the machine is off.•HDDs are very robust and can be used for many years without problems

Details about the Functionalities• Hard drives use magnetism to store information.• Platters are discs, one on top of the other spaced a few

millimetres apart where actual data is stored in 0's and 1's• Spindles rotates the platters.• Actuator is a motor responsible for moving or controlling

the hard drive head arm • Arms consist of copper heads mounted on its end• Copper heads are used to magnetize and demagnetize

using electricity to write or erase data• Platters : separated into different sectors and tracks• Tracks : rings on a disk where data can be written• Sectors: Subdivision of track on a magnetic disk.

Hard Disk Mechanism

Performance characteristics•Access Time: time taken before the drive actually transfers data. •Seek time: Time to find the correct track •Data transfer rate: Rate at which data can be retrieved from or stored to the disk.•RPM: Rotation of disk platters per minute . Eg 7200 rpm & 5400 rpm HDDs are available•Power Consumption Capacity

Things to be taken care of

•Prevent from physical damage•Avoid magnetizing the hard drive•Prevent from Excessive heating•Avoiding frequent on and off : the act of frequently spinning up and spinning down can cause additional attrition on top of the wear and tear of regular use•Use of surge protector from power surges

Dependencies•OS : During booting, the boot drive loads the system files from hard disk to RAM and executes them

•Processor : Speed of processor depends on hard disk.•Memory: If the RAM gets filled up then OS will start storing back and forth temporary data onto the hard drive.

Latest Market Updates

SSD:

•Stands for Solid State Drive

•Uses NAND based Flash memory

•No mechanical moving components

Comparison between HDD and SSD

•Durability: SSDs are more durable•Speed : Around 100 times faster than HDD•Power: Consumes less power .Around 3 times lesser than HDDs•Form factor: Lighter and smaller. 77 gms for SSD •Cost: Costlier than HDD •Noise and heat dissipation :Less noisier than HDDs and less heat dissipation .

Projection based on public information about HDD market

Advanced Technology Updates

•Hard drive companies are migrating away from the legacy sector size of 512 bytes to a larger, more efficient sector size of 4096 bytes, generally referred to as 4K sectors and enable the integration of stronger error correction algorithms to maintain data integrity at higher storage densities.

•New hard drive tech will help Seagate crack 5TB barrier in 2014, 20TB in 2020.Seagate has developed a new technology called 'Shingled Magnetic Recording' (SMR) Seagate recently made public its intention to develop and supply 20TB hard disk drives, under its SMR technology•SSHD: Capacity, performance and value•SSD + HDD=SSHD