Secondary storage refers to any device that can store data, in addition to main memory. Secondary storage devices are non-volatile and are typically high capacity, portable or both.
Factors affecting the choice of a secondary storage device include:
- speed (how quickly data can be accessed)
- cost per storage unit (i.e. price per gigabyte or megabyte)
- durability (toughness)
- portability (how easy it is to move it from one computer to another)
Uses, advantages and disadvantages of storage media:
| Storage device | Advantages | Disadvantages | Characteristics / Typical uses |
|---|---|---|---|
| Magnetic storage: Hard Disc Drive (HDD) | Relatively cheap per unit of storage. Fast access and retrieval times compared to other storage devices. | Can be easily damaged, will slow down and eventually break over time. Slower access than Solid State Drives. | The main storage device in most computer systems. |
| Optical storage: Blu-ray disk | Can hold a lot more data than a standard DVD, meaning it can store movies with better picture and sound quality. Portable. | More expensive than DVDs. Requires a Blu-ray player. Can lose data when scratched. | A laser reads from and writes to Blu-ray disks. Used to store HD movies and other HD recordings. |
| Electrical storage: Solid State Storage Devices (SSD) | Very compact in size and therefore very portable. High speed of data transfer and low power consumption. | Considerably more expensive per unit than magnetic storage. More vulnerable to abrupt power loss and electro-magnetic fields. | USB flash drives and solid state hard drives have replaced the traditional HDD in some new computers. Memory cards are used as a convenient and portable removable storage medium. |
