Storage
holds data, instruction and information for future use . A storage medium is
the physical material on which a computer keeps data, instruction and
information . For example hardware, flash drive ,USB. A storage device is the computer hardware that records and retrieves items to and from storage media.
Capacity is the number of bytes a storage medium can hold.
Access time can be measured in two ways :-
- · The amount of time it takes a storage device to locate an item on a storage medium
- · The time required to deliver an item from memory to the processor
HARD
DISK :-
A
hard disk contains one or more
inflexible, circular platters that use magnetic particles to store data,
instructions , and information. Hard disks can store data using longitudinal
recording or perpendicular recording.
Characteristic
of HARDWARE :-
· Capacity
· Platters
· Read/Write
· Cylinders
· Sector and
Tracks
· Revolutions
per minute
· Transfer
rate
· Access Time
Formatting is the process of dividing
the disk into tracks and sectors so that the operating system can store and
locate data and information on the disk.
RAID (redundant array of independent disks) is a group of
two or more integrated hard disks.
A
network attached storage (NAS)
device is a server connected to a network with the sole purpose of providing
storage.
How
Hard disk work ?
·
Actuator that moves the
read-write arm. In older hard drives, the actuators were stepper
motors. In most modern hard drives, voice coils are used instead. As their name suggests, these
are simple electromagnets, working rather like the moving coils that make
sounds in loudspeakers.
They position the read-write arm more quickly, precisely, and reliably than
stepper motors and are less sensitive to problems such as temperature
variations.
·
Read-write arm swings read-write
head back and forth across platter.
·
Central spindle allows platter to
rotate at high speed.
·
Magnetic platter stores
information in binary form.
·
Plug connections link hard drive
to circuit board in personal computer.
·
Read-write head is a tiny magnet
on the end of the read-write arm.
·
Circuit board on underside
controls the flow of data to and from the platter.
·
Flexible connector carries data
from circuit board to read-write head and platter.
·
Small spindle allows read-write
arm to swing across platter.
Memory card :-
A memory card is a
removable flash memory device that you insert and remove from a slot in a
computer, mobile device, or card reader/writer. For example – Flash card, Memory
card , Micro SDHC , Memory stick , Micro SD, Compact flash.
USB flash drives plug into a USB port on a computer or mobile device.
An Express Card module is a removable device that fits in an Express Card
slot. Developed
by the PCMCIA.
Commonly used in notebook computers.
Cloud storage is an Internet service that provides
storage to computer users. Cloud storage is an
Internet service that provides storage to computer users. Users subscribe to
cloud storage for a variety of reasons :-
- · Access files from any computer
- · Store large files instantaneously
- · Allow others to access their files
- · View time – critical data and image immediately
- · Store offsite backups
- · Provide data center functions.
What is optical disk ?
An optical disc consists of a flat, round, portable disc made of metal,
plastic, and lacquer that is written and read by a laser. Typically store
software, data, digital photos, movies, and music. Read only vs. rewritable. Optical discs commonly store items in a single
track that spirals from the center of the disc to the edge. Track is divided into evenly sized sectors.
Tape is a magnetically coated ribbon of plastic capable of
storing large amounts of data and information. A tape drive reads and writes data and information on a tape
A
magnetic stripe card contains a
magnetic stripe that stores information.
A
smart card stores data on a thin
microprocessor embedded in the card.
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