Secondary Storage Device

Secondary storageAlternatively referred to as external memory, secondary memory, and auxiliary storage, a secondary storage device is a non-volatile device that holds data until it is deleted or overwritten. Secondary storage is about two orders of magnitude cheaper than primary storage. Consequently, hard drives (a prime example of secondary storage) are the go-to solution for nearly all data kept on today's computers.

The image shows three types of storage, but off-line storage is a subset of secondary storage, as they both serve the same purpose and do not interact directly with the CPU.

Why does a computer need a secondary storage?

It is possible for a computer not to have or use a secondary storage (e.g. dumb terminal). However, for most computers and users secondary storage is required because of the need to permanently store some data to a computer. Without primary storage if you were working on a document and the power turned off everything would be lost because primary storage is a temporary. However, a computer with secondary storage that saved the file before the power turned off would be able to recover the last saved version of the file.

Related pages

Also see: Floppy drive terms, Hard drive terms, Off-line storage, Primary storage device, Storage device