Secondary Storage

• Secondary storage (backing storage) is non-volatile storage that is 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.

  This means that it is slower to access than primary storage.
• There are 4 types of Secondary storage:

  1. Magnetic storage.
  2. Optical storage.
  3. Solid state storage.
  4. Cloud storage.
• Magnetic storage:

  • A magnetic hard disk drive (HDD) is the most widely used type of Secondary storage in desktop computers.
  • It reads and writes data by moving a read/write head just nanometers above the spinning disk platter, interacting with its magnetic field.
• Floppy disks, another form of magnetic storage, are now outdated and have been replaced by faster, higher-capacity solid-state devices like USB drives.
• Magnetic tape is another form of magnetic storage that is still in use.

  • While it offers large storage capacity, data must be accessed in sequence (serial access).
  • This makes it primarily useful for companies to back up or archive vast amounts of data.
• Magnetic storage characteristics:

  • Large capacity.
  • Cheaper cost per gigabyte than solid state.
  • Not durable.
  • Not portable when powered on. Moving can damage the device.
  • Slow access speed but faster than optical storage.
• Optical storage uses a laser to project beams of light onto a spinning disc This allows it to read data from a CD, DVD, or a Blu-ray.

  This makes optical storage the slowest of the 4 types of Secondary storage.
• Disc drives are traditionally internal, but external disc drives can be bought for devices like laptops.
• Optical storage characteristics:

  • Low Capacity: 700 MB (CD), 4.7 GB (DVD), 25GB (Blu-ray).
  • Not durable - discs are fragile and can break or scratch easily.
  • Very portable - discs are thin.
  • Cheap to buy in bulk.
  • Slowest access speed.
• Magnetic Disks are spelled with k and Optical Discs have a c.
• Solid State storage have no moving parts.
• Solid State Drives (SSDs) are replacing magnetic HDDs (Hard Disk Drives) in modern computers and video game consoles.

  This is because they are generally quieter, faster, and use less power.
• Another type of solid state storage is a USB flash drive (USB stick).

  It is used to transport files 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:

  • High capacity.
  • More expensive cost per gigabyte than magnetic.
  • Usually durable but cheap USB sticks can snap or break.
  • Very portable - the small size of USB sticks and memory cards mean they can fit easily in a bag or pocket.
  • Fastest access speed - this is because they contain no moving parts.
• Cloud storage:

  When you store data in the cloud, using services such as Google Drive or Dropbox, your data is stored on large servers owned by the hosting company.

  The hosting company is responsible for keeping the servers running and making your data accessible on the internet.
• Cloud storage is very convenient as it allows people to work on a file at the same time and it can be accessed from different devices.
• Data in cloud storage will become inaccessible if the internet connection fails, or the servers are attacked.
• Cloud storage characteristics:

  • Huge capacity - you can upgrade your subscription if you need more storage.
  • Access speed depends on your internet connection.
  • Typically free for a certain amount of storage - users can then buy a subscription to cover their needs.