Solid-state drive

See also solid state disk, SSD and flash disk.

This article discusses the characteristics of the solid state drive, its origins as a solid state disk for mission-critical applications, technological advances in NAND flash memory that are now making the solid state drive cost-effective for mobile computing in enterprise and consumer electronics markets, and its benefits over the hard disk drive.

Reliable data storage with non-volatile memory

File:Open HDD and SSD.JPG

Open casing of 2.5” traditional hard disk drive (left) and solid state drive (center), a drop-in replacement for hard disk drives for mobile computing.

The disassembled components of a hard disk drive (left) and of the PCB and components of a solid state drive (right).

A flash-based solid state drive is primarily a data storage device for use in mobile computing such as notebook PCs and sub-notebooks in the enterprise and consumer electronics space, desktop servers, point of service systems and other applications that traditionally use a hard disk drive.

A solid state drive is based on non-volatile memory instead of the spinning platter and mechanical head found in a conventional hard disk drive. With no moving parts, a solid state drive eliminates seek time, latency and other electro-mechanical delays and failures associated with a conventional hard disk drive.

Origins of the solid state disk

msystems ([1]) was the first company to introduce flash-based solid state disks in 1995. Since then, they have been used successfully as hard disk drive replacements by the military and aerospace industries, as well as other mission-critical applications that require the exceptional mean time between failure (MTBF) rates that solid state disks achieve based on their ability to withstand extreme shock, vibration and temperature ranges.

NAND flash cost and capacity considerations

Until recently, however, solid state disks were too costly for mobile computing. As flash manufacturers transition from NOR flash to single-level cell (SLC) NAND flash and most recently to multi-level cell (MLC) NAND flash to maximize silicon die usage and reduce associated costs, "solid state disks" are now being more accurately renamed "solid state drives" - they have no disks but function as drives - for mobile computing in the enterprise and consumer electronics space. This technology trend is accompanied by an annual 50% decline in raw flash material costs while capacities continue to double at the same rate. As a result, flash-based solid state drives are becoming increasingly popular in markets such as notebook PCs and sub-notebooks for enterprises, Ultra-Mobile PCs (UMPC), and Tablet PCs for the healthcare and consumer electronics sectors.

Advantages of solid state drive over hard disk drive

The solid state drive provides major advantages in the mobile computing space over the hard disk drive:

• Boosts operating performance up to 2 times for operating system boot and up to 4 times for application launch/runtime
• Boosts input/out per second (IOPS) performance up to 100 times
• Maintains fixed performance that does not deteriorate as the media fills up
• Delivers up to 50% power savings to extend battery life
• Improves reliability by its ability to endure extreme shock, vibration and temperatures
• Improves mean time between failure (MTBF) rates up to 10 times
• Reduces heat dissipation
• Reduces weight by up to 50%
• Completely eliminates spin-up and operational noise