Secondary Storage

• Secondary storage is non-volatile storage used to save and store data that can be accessed repeatedly.
• Secondary storage is not directly embedded on the motherboard and therefore further away from the CPU so it is slower to access then primary storage.
• Storage Characteristics you should know:

  • CAPACITY: The maximum amount of data that can be stored on the device.
  • DURABILITY: The strength of the device, to last without breaking.
  • PORTABILITY: How easy it is to carry the device around.
  • ACCESS SPEED: How quickly data on the device can be read or edited.
  • COST: The average price it costs to purchase the storage device.
  • RELIABILITY: The likelihood of the device continuing to perform well over time.
• A magnetic hard disk drive (HDD) is the most common form of secondary storage within desktop computers.
• A read/write head moves nanometres above the disk platter and uses the magnetic field of the platter to read or edit data.
• An obsolete type of magnetic storage is a floppy disk but these have been replaced by solid state devices such as USB sticks which are much faster and have a much higher capacity.
• Another type of magnetic storage that is still used is magnetic tape.
• Magnetic tape has a high storage capacity but data has to be accessed in order so it is generally only used by companies to back up or archive large amounts of data.
• MAGNETIC STORAGE CHARACTERISITCS:

  • LARGE CAPACITY and cheaper COST per gigabyte than solid state.
  • Modern external HDDS are small and well protected so they are DURABLE and PORTABLE.
  • Slower ACCESS SPEED than solid state but faster than optical storage.
• Optical storage uses a laser to project beams of light onto a spinning disc, allowing it to read data from a CD, DVD or Blu-Ray.
• This makes optical storage the slowest of the four types of secondary storage.
• Disc drives are traditionally internal but external disc drivers can be bought for devices like laptops.
• OPTICAL STORAGE CHARACTERISTICS:

  • LOW CAPACITY: 700 MB (CD), 4.7 GB (DVD), 25 GB (Blu-Ray).
  • NOT DURABLE because discs are very fragile and can break or scratch very easily.
  • Discs are THIN and very PORTABLE.
  • Very cheap to buy in bulk.
  • Optical discs have the slowest ACCESS SPEED.
• There are no moving parts in solid state storage.
• SSDs are replacing magnetic HDDs in modern computers and video game consoles because they are generally quieter, faster and use less power.
• A USB flash drive is another type of solid state storage that is used to transport files easily because of its small size.
• Memory cards, like the SD card in a digital camera or a Micro SD card in a smartphone, are another example of solid state storage.
• SOLID STATE CHARACTERISTICS:

  • More EXPENSIVE COST per gigabyte than magnetic.
  • Usually DURABLE but cheap USB sticks can snap or break.
  • The small size of USB sticks and memory cards mean they are very PORTABLE and can fit easily in a bag or pocket.
  • Solid State Storage have a high CAPACITY and the fastest ACCESS SPEED because they contain no moving parts.