Storage devices and media

Secondary storage includes…

all non-volatile storage devices that are not part of primary memory

what is the storage capacity of these devices much___ than

much larger than Ram and Rom

data ______ is much longer

data access time

three types of technology used by secondary storage devices (3)

-magnetic

-optical

-solid state

magnetic media rely on what property

property that certain materials have magnetic porperties

what can magnetic properties be used for

store data

Magnetic media are a type of permanent storage unless what (2)

-they are overwritten

-deleted by system of the user

overwritten data meaning

new data replaces old data

Two common magnetic devices

-magnetic tape drive

-hard disk drive

what do magnetic tape drums consist of

a plastic tape coated in a magnetic oxide layer

___ have different ____signature

data stored (1s and 0’s) have different magnetic signatures

what do different magnetic signatures allow

allow a read and write head to read and write data

use of magnetic tapes (2)

-batch processing

-backup of data for long term storage

magnetic tape advantages (3)

-less expensive than SSD and HDD

-vast storage capacity

-very good data transfer rates

disadvantages (2)

-affected by magnetic fields

-slow data access time

how is data stored in HDD’s

data stored on disk surfaces called platters

what are platters coated in

magnetic tape

what do the read write heads do and what do they contain

read/write heads with tiny magnets hover close to each disk surface

what does the hovering of the read/write heads allow

allows data to be written and read

what are actuators used for

used to move the read/write heads

where is data stored on the platters and how is it broke up

data stored on tracks which is broken up into sectors

how are sectors mapped

using a file allocation table (FAT)

what does FAT show

shows which sectors are free and which contain data

what do magnetic disk drives suffer from

latency

latency

time taken for a specific block of data on a track to rotate round tot he read/write head

HDD uses (2)

-store operating systems, system software, apps, and data

-website and file servers on networks used in real time systems

HDD advantages (2)

-fast data transfer rates

-large storage capacities

HDD disadvantages (3)

-slow data access time

-suffer from latency

-fairly easily damaged

Main uses of portable disk drives (2)

-backing up data

-allowing data to be transferred between computers

Optical media devices

use lasers to read and write data into plastic disks

disks rely on optical properties of… (2)

-certain chemical dyes

-metal alloys

what do the properties enable

enable the storage of 1’s and 0’s

most common types of optical storage devices (2)

-CD’s and DVD’s

-Blu-ray disks

CD and DVD can be designed as (3)

-write one R

-read/write many times RW

-read only ROM

all disks have (2)

-thin coating of alloy

-light sensitive organic dye

CD/DVD R uses (4)

-transfer of data between computers

-music recording (CD)

-movie recording (DVD)

CD/DVD R advantages (1)

cheaper than RW disks

CD/DVD R disadvantages (2)

-can only read once

-disk discarded if error occurs

CD/DVD RW uses (2)

-record tv programs over and over

-file backup

CD/DVD RW advantages (2)

-not as wasteful as R

-can go through several read write operations

CD/DVD RW disadvantages (2)

-relatively expensive

-possible to overwrite data

CD/DVD ROM uses (1)

permanent storage for things like games, music

CD/DVD ROM advantages (2)

-less expensive than HDD

-data is permanently stored

CD/DVD ROM disadvantages (1)

-isn’t possible to change data

blu-ray disks

optical medium that uses blue laser light

how does the wavelength differ

shorter wavelength than red lapse light

shorter wavelength advantage

increased storage capacity compared to DVD

blu ray disks uses (2)

-storing high definition movies

-backing up data

blu ray disks advantages (3)

large storage capacity

fast data transfer rates

data encryption built in for data security

blu ray disks disadvantages (1)

more expensive than DVD

SSD

non volatile rewritable data storage device

ssd uses (2)

storage backing

laptops/tablets

why are ssd’s used in laptops and tablets

cause of their small sizes

ssd advantages

-no moving parts: less likely to malfunction

-much lighter in weight

-permanent deletion of data unlike HDD

pen drives

ssd devices that connect to computer via usb ports

memory card types (3)

SD cards

XD cards

CFast cards