1.3 Storage 3: capacity, speed and cost

Question 1

capacity of magnetic storage

hard disc and DAT tape

Answer 1

very large 1-2TB is common in home computers

can store 1000 to 2000 movies (assuming an average size of 1GB)

can be used to backup data, as DAT tape is cheap and can be stored for a very long time

Question 2

capacity of optical storage

CD-R, blue ray and DVDs

Answer 2

low

blue ray stores <50 GB
CDs store 700MB
DVDs store 4.7 GB
can store 4 movies

Question 3

capacity of solid state

SD cards, SSDs and USB drives

Answer 3

moderate

SSDs range from 128-512 GB but the capacity is rapidly increasing

can store up to 500 movies

SD cards store up to 32 GB

Question 4

speed of magnetic storage

Answer 4

fast

random access: data can be read instantly from any part of the disc

can find and supply the required data in milliseconds

Question 5

speed of optical storage

Answer 5

slow

Question 6

speed of solid state

Answer 6

very fast

can access data in nanoseconds

Question 7

cost of magnetic

Answer 7

very low

magnetic drives storing terabytes of data are common in most home computers

Question 8

cost of optical

Answer 8

very low

Question 9

cost of solid state

Answer 9

more expensive than magnetic drives and optical devices

solid state storage is relatively new technology
storage capacity is rapidly increasing and the cost is falling

Question 10

A school has a number of different data storage requirements

State which type of secondary storage is most suitable for each of the purposes listed below. Give a reason for your choice

a) hand held data-logging devices used for fieldwork
b) storage drives on the school’s file server to save all the students’ work
c) copies of a video of a school production to be given to parents [6]

Answer 10

a) solid state
very fast access speed for taking readings and not sensitive to being moved around
very light so easy to carry

b) magnetic
very large capacity, reliable and low cost

c) optical
discs are cheap and portable and most home computers can access them

Question 11

Explain why nowadays many laptops and desktop computers have built in sold state storage rather than hard drive discs [3]

Answer 11

SSDs have faster data access speeds than hard disc drives

SSDs have no moving parts and are not damaged if the computer is moved or dropped

the storage capacity of SSDs is rapidly increasing and cost is falling

SSDs have lower power consumption and make the computer more energy efficient

SSDs are quieter as there are no rotating metal platters