Solid-state storage

Solid-state storage (SSS) is non-volatile computer storage that has no moving parts; it uses only electronic circuits. This solid-state design differs from the commonly used competing technology of electromechanical magnetic storage which uses moving media coated with magnetic material. Generally, SSS is much faster but more expensive per unit of storage. SSS devices typically use flash memory, but some use battery-backed random-access memory (RAM). Devices come in various types, form factors, storage sizes, and interfacing options to satisfy application requirements for many computer systems and appliances. Historically, computer system secondary storage has been implemented to leverage magnetic properties of surface coatings applied to rotating platters (in hard disk drives and floppy disks) or linearly moving strips of plastic film (in tape drives). Pairing such magnetic media with read/write heads allows data to be written by separately magnetizing small sections of the ferromagnetic coating, and read later by detecting the transitions in magnetization. For the data to be read or written, exact sections of the magnetic media need to pass under the read/write heads that flow closely to the media surface; as a result, reading or writing data imposes delays required for the positioning of magnetic media and heads, with the delays differing depending on the actual technology. Over time, advancements in central processing unit (CPU) speed has driven innovation in secondary storage technology. One such innovation, flash memory, is a non-volatile storage medium that can be electrically erased and reprogrammed.