Storage Devices

Storage Devices are components of a computer system that provide a permanent place for data to be stored. In contrast with memory, storage is always non volatile - when power is lost to the device, data is sustained. In general storage devices are slower than memory due to multiple things:

• The actual storage medium (i.e the physical location that data is stored) is slower to access or modify
  • This is often the case for spinning disks, such as Hard Disk Drives or Optical Discs. However, fast storage such as SSDs still fails to reach the speed of modern RAM.
• The link to the CPU is more complex or slower, for example going through the southbridge
  • This is true for almost all storage except modern PCI-express SSDs; taking more direct routes to the CPU (such as through PCI-express lanes) allows reduced latency and increased speed
• The type of connection is limited in speed
  • This is true for most portable storage devices: Portable removable drives that use connections such as USB or thunderbolt are limited by the maximum bandwidth of the connector

Types of Storage Devices

Type	Common Varieties	Pros	Cons
Magnetic	Hard Disk Drive	Cheap, High Capacity, Long Lifespan, read/writes not limited	Fragile Platter, Average Speed, Mechanical components can break
Flash Memory	Solid State Drive (SSD), Integrated eMMC Storage, USB Flash Drives, SD Cards	High Speed & Low Latency, Resistant to physical shock	Expensive, Low/Medium Capacity, Limited read/write cycles
Optical	Compact Disc (CD), Digital Versatile Disc (DVD), Blu-Ray	High portability, Cheap unit cost	Very slow, High cost per GB, Low capacity, Fragile, Shorter lifespan (disc rot)