1.3 Storage

Question 1

What are the three tiers of storage?

Answer 1

Primary
Secondary
Tertiary

Question 2

Define primary storage.

Give four examples

Answer 2

Memory areas that the CPU access is directly and quickly. Has the fastest read/write speeds and is mostly volatile

This includes registers, cash, ROM and RAM

Question 3

Define secondary storage

Answer 3

Nonvolatile, read/write, permanent memory which is not directly accessed by the CPU, and his data must be transferred into main memory before being processed by the CPU

Question 4

Define tertiary storage

Answer 4

External, non-volatile, high capacity memory used for archives and backups by large companies

Question 5

Give a typical example of tertiary storage

Answer 5

A magnetic tape library which may use a robotic arm to access the tapes

Question 6

Why is secondary storage required?

Answer 6

A way of storing data and files permanently and long-term – must be non-volatile and read/writeable

Question 7

How is data stored on optical discs?

Answer 7

As microscopic indentations (pits and lands representing 0s and 1s) on a disc’s reflective surface in a spiral track running from inside to outside of disc

Question 8

What is the capacity of a CD? DVD? BD?

Answer 8

CD = 700 MB
DVD = 4.7 GB
BD = 25 GB +

Question 9

Why are optical discs falling out of use?

Answer 9

Streaming and downloading as internet speeds have increased remove the need for optical discs

Modern devices such as smartphones don’t have optical drives

Can’t compete with flash memory for backups – low capacity, slow read/write speed and poor reliability of read/write discs

Question 10

How is data stored in magnetic storage?

Answer 10

As opposite magnetic polarities in sectors within tracks on a magnetise metal platter, which makes up one of many stacked on top of each other, spinning at 5400 - 15000 rpm

Question 11

What is the traditional internal storage for a computer?

Answer 11

HDDs

Question 12

What is a read/write head made of?

Answer 12

Electromagnets

Question 13

What are the advantages of SDDs over HDDs?

Answer 13

Faster
Don’t need defragmenting 
No noise
No heat
More shock-proof

Question 14

What is flash memory?

Answer 14

Data is stored in arrays of transistors, which are either on or off, representing zeros and ones

Question 15

Faster boot up times and faster opening of programs and files is given by …

Answer 15

Solid state storage

Question 16

What is the physical appearance of magnetic tape? What does it require?

Answer 16

Comes in plastic cassettes which require a special tape-drive to read/write

Question 17

How is data written into magnetic tape?

Answer 17

Sequentially

Question 18

What happens if an HDD is hit?

Answer 18

The data is corrupted when the head hits the platters

Question 19

Reliability of optical discs

Answer 19

Stored data degrade over time

Question 20

Data access time of HDDs

Answer 20

Milliseconds

Question 21

Data access time of SDDs

Answer 21

Nanoseconds

Question 22

How is data accessed on an HDD?

Answer 22

Random Access

Question 23

Cost of optical discs

Answer 23

Very low

Question 24

Why is the cost of solid state so high?

Answer 24

Relatively young technology

Question 25

Capacity of a typical HDD

Answer 25

1 - 2 TB

Question 26

Capacity of a typical SDD

Answer 26

128 - 512 GB

Question 27

What percentage overheads do you need when calculating data capacity?

When do we use this in our calculations?

Answer 27

10%

Only use if the question specifies