Solid-state storage

Solid-state storage (SSS) is a type of non-volatile computer storage that stores and retrieves digital information using only electronic circuits, without any involvement of moving mechanical parts. This differs fundamentally from the traditional electromechanical storage, which records data using rotating or linearly moving media coated with magnetic material. Solid-state storage devices typically store data using electrically-programmable non-volatile flash memory, however some devices use battery-backed volatile random-access memory (RAM). Having no moving mechanical parts, solid-state storage is much faster than traditional electromechanical storage; as a downside, solid-state storage is significantly more expensive and suffers from the write amplification phenomenon. Solid-state storage devices come in various types, form factors, sizes of storage space, and interfacing options to satisfy application requirements for many different types of computer systems and appliances. Historically, secondary storage in computer systems has been implemented primarily by using magnetic properties of the surface coatings applied to rotating platters (in hard disk drives and floppy disks) or linearly moving narrow 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, the performance gap between the central processing units (CPUs) and electromechanical storage (hard disk drives and their RAID setups) widened, requiring advancements in the secondary storage technology.