Secondary Storage

• Secondary Storage non-volatile

  non-volatile but read/write speeds are slower
• Common types of storage

  Solid State, Optical, Magnetic
• Solid State


  Flash Drive

  Solid State Drive
• Optical 


  CD

  DVD

  Blu-Ray Disc
• Magnetic

  Internal Hard Disk

  External Hard Disk
• Advantages and Disadvantages based on

  Capacity

  Speed

  Portability

  Reliability

  Durability

  Cost
• Capacity

  Optical < Solid State < Magnetic

  • CD → 650 Mb
  • DVD → 4.7GB (single layer), 9GB (double)
  • Blu-ray disc → 25GB (single), 50GB (double)
  • Internal Hard Disk → (up to) 4Tb
  • External Hard Disk → (up to) 4Tb
  • Flash Drive → (up to) 512 GB
  • Solid State Drive → 64Gb - 256Gb
• Best for Capacity 


  Magnetic Storage
• Speed

  Optical Discs < Magnetic Tapes < Solid State Drive

  • CD → Slower than hard disk but faster than tape
  • DVD → Slower than hard disk but faster than tape
  • Blu-ray Disc → Slower than hard disk but faster than tape
  • Internal Hard Disk → Fast
  • External Hard Disk → slower than internal hard disk but faster than CD/DVD
  • Flash Drive → slower than hard disk but faster than CD/DVD
  • Solid State Drive → very fast
• Best for Speed

  Solid State
• Portability

  Magnetic < Optical < Solid State

  • CD → fairly portable, too big to fit in pocket but can fit into bag
  • DVD→ fairly portable, too big to fit in pocket but can fit into bag
  • Blu-Ray → fairly portable, too big to fit in pocket but can fit into bag
  • Internal Hard Disk → Not designed to be portable, is attached directly to computer chassis
  • External Hard Disk → Fairly portable, comes in various sizes but normally larger than CD/USB stick
  • Flash Drive → very portable, fit in pocket
  • Solid, State Drive → fairly portable, comes in various sizes, normally bigger than CD
• Best for Portability

  Solid State / Optical

  Flash Drive
• Reliability

  Optical < Magnetic < Solid State

  • CD→ not very reliable
  • DVD → not very reliable
  • Blu-ray → not very reliable
  • Internal Hard Disk → Fairly reliable
  • External Hard Disk → Fairly reliable
  • Flash Drive → usually very reliable
  • Solid State Drive → very reliable
• Best for Reliability

  Solid State - Solid State Drive
• Durability

  Optical < Magnetic < Solid State

  • CD → can easily be scratched, needs protecting from heat
  • DVD→ can easily be scratched, needs protecting from heat
  • Blu-Ray - can easily be scratched, needs protecting from heat
  • Internal Hard Disk → can be damaged if dropped or exposed to extreme heat / strong magnetic fields
  • External Hard Disk → an be damaged if dropped or exposed to extreme heat / strong magnetic fields
  • Flash Drive → very durable, USb connecter can be snapped off rendering device unusable
  • Solid State Drive → very durable, can be dropped without damaging contents
• Best for Durability 


  Solid State
• Secondary Storage

  long-term memory

  storing on hard-drive