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

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

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.

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

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

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

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

Optical Storage

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

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

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