Flash drive
From Wikipedia, the free encyclopedia
A Flash drive is a storage device that uses flash memory rather than conventional spinning platters to store data. Unlike USB flash drives and memory cards, flash drives tend to physically imitate conventional hard drives in size, shape, and interface so that they may act as a replacement for hard drives. With nothing being mechanically driven in a flash drive, the name may be seen as either a misnomer or as a generalization of the word "drive".
These products have typically been used as low power, rugged replacements for hard drives in products exposed to harsh conditions. They have also recently started to emerge in small laptops such as the Eee PC and others. Unlike DRAM or SRAM-based solid-state drives, flash drives are inherently non-volatile and do not require battery backup.
As each individual flash memory cell tend to fail after a few million erase cycles, early flash devices were unsuitable for frequently updated data such as swap files and similar. To address this problem, flash disk vendors introduced wear-leveling techniques that transparently relocate writes to physical locations that have been less utilized. Modern devices also inherently survive more erase cycles.
Another use for flash drives is to run lightweight operating systems designed specifically for turning general-purpose PCs into network appliances comparable to more expensive routers and firewalls. In this situation, a write protected flash drive containing the whole operating system is used to boot the system. A similar system could boot from CD, floppy disk or a traditional hard drive but flash memory is a good choice because of very low power consumption and failure rate.
Windows Vista, the latest release of Microsoft Windows, requires the use of a hybrid hard disk for laptops to be certified as "Vista Premium capable" in order to reduce overall power consumption, increase access speed, and extend battery life [1]. It is widely assumed that this trend will increase over time as the cost of flash drives decreases and the performance needs of consumer electronics continue to increase.
[edit] Notes
[edit] See also
- RAM disk - virtual SSD drive which uses a segment of a computer's main memory as secondary storage.
- Solid-state drive - A DRAM or flash-based data storage intended primarily to increase performance.
- USB flash drive - Flash-based data storage for mobile computing
- Hybrid drive - A hard disk which uses a large buffer of flash memory to improve performance.
- Memory card - a solid-state electronic data storage device used with digital cameras, handheld and laptop computers and other portable devices.
- PC card - A peripheral interface for laptop computers, originally designed for memory expansion.
