Magnetic, Optical & Solid State Storage

Magnetic Storage Devices

Magnetic-Storage-Devices-Revision-Sheet

These are the oldest of the commonly used storage devices, but are still the most widely used.

• Magnetic Hard Drives are used to store data and programs on desktops and laptops
• Magnetic tape drives are usually used for large server / systems backups.

Advantages

• Cheap Storage per MB (especially tape drives!)
• Relatively quick read / write speeds.

Disadvantages

• Easily broken if dropped
• Slow read /write compared to new SSD drives.
• High energy uses as it uses moving parts (lower battery life on laptops)

 

Further Watching  – How do Magnetic Stripe Cards work?

 

Optical Storage Devices

Optical-Storage-Devices-Revision-Sheet

Optical Storages used to be incredibly popular up until the last couple of years where cloud storage and the rise of video and game streaming services have massively reduced their popularity.

Types of optical storage devices:

• CD Drives  (700MB)
• DVD Drives  (4.7GB)
• BluRay Drives (50GB)

Optical storage devices offer cheap and portable high capacity secondary storage. Far more portable than an internal hard-drive, which makes them good for small / medium size backups and great for sending through the post.

 

How they work

Optical storage devices work by firing a laser at the surface of a spinning disk. The disc is covered in a pattern of pits in the CD surface. As the laser hits the pits it is reflected and the pattern of pits it detected by a laser detector.

Solid State Storage Devices

Solid-State-Devices-Revision-Sheet

Solid state devices are the newest form of storage to emerge. The technology is used in Hard Drives, SD Cards and USB sticks. Solid state storage devices work by storing data in flash chips electronically. They are still more expensive than traditional storage devices but the price per GB is falling all the time.

Advantages

• Very fast read / write speeds.
• Shock resistant as there are no moving parts to break if knocked
• No moving parts so longer battery life ( great for laptops / tablets / smartphones)

Disadvantages

• More expensive per GB of storage
• Limited life span, as each flash cell can only be written to a limited number of times.

 

 

 

Common Storage Device Comparisons

Device Type	Capacity	Speed	Portability	Durability	Reliability	Cost
Magnetic Hard Drive HDD	High Capacity(2TB +)	Relatively Slow Read / Write Speeds	Not very portable and quite heavy	Long life span, but susceptible to damage / data corruption if dropped	Very Reliable	Cheapest form of main secondary storage
Solid State Hard Drive	Medium Capacity <1TB	Exceptionally fast read / write speeds	More portable than HDD but not as portable as other types, as usually inside the pc	No moving parts, so very durable	Quite reliable, up to 5 years.	Twice the price of HDD Drives
SD Card	Low / Medium Capacity <256GB	Very fast read / write, as flash memory	Extremely portable	Won’t be damaged if dropped, but easy to lose and susceptible to water damage	Not very reliable, prone to stop working over time	Quite high cost per GB
Pen Drive	Low / Medium Capacity <256GB	Very fast read / write, as flash memory	Extremely portable	Won’t be damaged if dropped, but easy to lose and susceptible to water damage	Not very reliable, prone to stop working over time	Quite high cost per GB
CD (Optical Drive)	Low Capacity 700MB	Very Slow Read / Write speed	quite portable, cheap to mail, will work in many devices (PCs, Music Players, Car stereos)	Easy to scratch and data loss easy	Not very reliable, prone to stop working over time	Very Low cost per unit(10p)
DVD	Low Capacity 4.7GB	Quite Slow Read / Write Speed	quite portable, cheap to mail	Easy to scratch and data loss easy	Not very reliable, prone to stop working over time	Very Low cost per unit (10p)
Blu-ray	Medium Capacity 50GB+	Medium Read write speed	quite portable, cheap to mail	Easy to scratch and data loss easy	Not very reliable, prone to stop working over time	Very Low cost per unitl (10p)
Magnetic Tape Drive	Massive Capacity	Very Slow Read / Write speed. Sequential read / write only	quite portable, cheap to mail	Generally long lasting	Medium reliability over time	Very, very low cost per TB
Cloud Storage	Effectively infinite storage	Depends on internet speed, but quite slow	Can access anywhere there is access to internet	Very durable, due to backups and offsite storage.	As reliable as internet connection.	Cheap per GB, but may require monthly subscription

Resources

AI Assisted Teaching & Learning Resources

Secondary Storage Devices Worksheet

Secondary Storage Devices Worksheet Version 2

Secondary Storage Devices Kahoot

Secondary Storage Devices Kahoot 2

Past Paper Exam Questions

0478/11 Paper 1 Theory May/June 2016  Qn 11

0478/12 – Paper 1 Theory May/June 2016 Qn 10

0478/13 – Paper 1 Theory May/June 2016 Qn11

0478/11 – Paper 1 Theory October/November 2017 qn 9a (CDs)

0478/11 Paper 1 Theory October/November 2018 Qn 5c