1. Lesson Objectives Aims You should be able to:
Explain the need for secondary storage
Describe optical, magnetic and solid state storage
Select suitable storage devices and media for a given application

2. The need for secondary storage
MOST memory is:
Volatile
Fast to access
Fixed in place (non-removable)
Relatively small in capacity
Therefore there is a need for:
Non-volatile storage
High storage capacity
Reliability
Portability

3. Secondary storage
Any large, non volatile method of storage can be classed as “secondary”
It is used to hold:
All programs and data
Usually data that is not currently in use
Anything which needs to persist from one use (power cycle) to the next.

4. Types
There are three main types:
Magnetic
Optical
Solid state (flash)

5. Magnetic Storage
Magnetic storage media and devices store data in the form of tiny magnetised particles.
These dots are created, read and erased using magnetic fields created by very tiny electromagnets.
You are literally storing your data on rust..
Examples:
Hard disk drive
Portable hard disk drive
Magnetic tapes

6. Solid State Storage
The term ‘solid-state’ essentially means ‘no moving parts’ (no reels of tape, no spinning discs, no laser beams).
The data stored on solid state backing storage is rewritable.
It includes:
Memory sticks
Flash memory cards

7. Optical Storage The use of lasers to read and write data
Lasers are reflected off the surface of a disc
The direction of reflection or time it takes to reflect the laser dictates 0 or 1

8. Optical Storage

9. The final word on system performance
The type of CPU, Memory and Storage you choose all has an effect on performance.
To increase performance:
CPU -> More cores, more cache, more GHZ
RAM -> More = more space, less need to visit slow storage
HDD -> SSD -> SSD has no moving parts so is WAY faster
GPU -> New GPU -> Faster graphics crunching

10. Complete the table Type of Storage Typical Capacity Speed Portability
Durability
Reliability

11. Scenarios
Recommend and justify a type of storage to be used in the following situations:
Backing up the school shared area every night
Working on a video editing project both at home and school
Storing data on a slim laptop/ultrabook
Increasing the performance of an old computer
Storing large amounts of data on a network
Storing data in a system which constantly updates, reads and writes data
Storing a movie to watch on a TV