Secondary Storage

Question 1

What are the 5 main uses of secondary storage?

Answer 1

• Long term storage
• Back up data
• More storage space for things like picutres
• Send data over a network
• Easily transport files

Question 2

What are the 3 main types of secondary storage?

Answer 2

• Magnetic
• Optical (CD’s, Blu-rays, DVD’s)
• Solid State Discs (USB’s Flash Drives)

(Secondary storage are mostly external hardware devices to store long term data)

Question 3

Describe how Magnetic Storage Disks work. Describe 4 disadvantages and advantages of MSD’s

Answer 3

• use magnetic fields to magnetise individual sections of a metal spinning disk, with each section representing one bit
  > A demagnetised section represents 0; magnetised is 1.
• As the disk spins, read/write heads move over the surface of the disk:
  > It writes by magnetising or demagnetising sections
  > It reads by taking note of which sections are magnetised or not

Advantages:

• Can hold alot of storage
• Quicker to store and retrieve data that optical disks
• Data is not lost (non-volitile)
• Cheap storage

Disadvantages:

• Contains moving parts, making it easy to damage
• The surface of the disk can be scratched, losing data
• Uses a lot of energy
• Can be noisy

Question 4

Describe how Optical Storage Devices Work. What are the 3 forms of OSD’s? What are advantages and disadvantages of OSD’s?

Answer 4

• A laser scans the surface of a spinning disk, which cotains hollows and pits (representing 1, and 0,s)
• Hollows will reflect the laser back (1) and pits will scatter the laser (0)
• ROM media, which has preinstalled data that is unchangeable
• R media, which is a clean disk, which can have data written on it though a laser etching pits and hollows (this cannot be changed onced stored)
• RW media, which is the same as R, except can be changed more than once

Advantages:

• Easy to store and carry
• Can be read by multiple devices
• Can last a long time if taken care of properly

Disadvantages:

• Easily scratched
• Data written on R drived or ROM cannot be changed (permanently fixed)
• Can be Expensive

(These are like DVD’s, Blu-Rays etc)

Question 5

Describe Solid State Disks. What are the advantages and disadvantages of SSD’s

Answer 5

• They contain no moving parts and are usually in the forms of USB’s or SD cards.
• They use special transistors to store and keep data even when not used

Advantages:

• Lightweight and convenient
• Portable data medium
• Durable (especially because no moving parts)
• Quiet and easy to install

Disadvantages:

• Cannot carry too much data
• Can be quite expensive (cost per MB higher than Magnetic Disk Drives)

Question 6

What is Cloud Storage? What are the advantages and Disadvantages?

Answer 6

• Data stored online in a cloud, which can be distibuted and accessed by multiple users connected to that cloud via the internet
• The cloud is stored on Magnetic and Solid State Storage held in one remote location
  ( e.g. apple icloud or microsoft cloud)

Advantages:

• Limitless data
• Automatic backups
• Acessable from anywhere with internet
• Accessable from multiple devices (unlike MSD’s which need to be installed)

Disadvantages:

• Needs internet connection
• Can be slow to access some times
• The cloud host is in control of this information
• Sometimes you need to pay subsciption for usage