What Is SSD ?

A solid-state drive (SSD), sometimes called a solid-state disk or electronic disk, is a data storage device that uses integrated circuit assemblies as memory to store data persistently. SSD technology uses electronic interfaces compatible with traditional block I/O hard disk drives. SSDs do not employ any moving mechanical components, which distinguishes them from traditional magnetic disks such as hard disk drives (HDDs) or floppy disk, which are electromechanical devices containing spinning disks and movable read/write heads. Compared to electromechanical disks, SSDs are typically less susceptible to physical shock, are silent, have lower access time and latency, but are more expensive per unit of storage.
SSDs share the input/output interface technology developed for hard disk drives, thus permitting simple replacement for most applications.
As of 2010, most SSDs use NAND-based flash memory, which retains data without power. For applications requiring fast access, but not necessarily data persistence after power loss, SSDs may be constructed from random-access memory (RAM). Such devices may employ separate power sources, such as batteries, to maintain data after power loss.
Hybrid drives combine the features of SSD and HDD in the same unit, containing a large hard disk and an SSD cache to improve performance of frequently accessed data. These devices may offer near-SSD performance for many applications.

HISTORY:



Early SSDs using RAM and similar technology
The origins of SSDs came from the 1950s using two similar technologies, magnetic core memory and card capacitor read-only store (CCROS). These auxiliary memory units, as they were called at the time, emerged during the era of vacuum tube computers. But with the introduction of cheaper drum storage units, their use was discontinued.
Later, in the 1970s and 1980s, SSDs were implemented in semiconductor memory for early supercomputers of IBM, Amdahl and Cray; however, the prohibitively high price of the built-to-order SSDs made them quite seldom used. In the late 1970s, General Instruments produced an electrically alterable ROM (EAROM) which operated somewhat like the later NAND flash memory. But a 10-year life was not achievable, and many companies abandoned the technology. In 1976 Dataram started selling a product called BULK CORE, which provided up to 2MB of solid state storage compatible with DEC and Data General computers. In 1978, Texas Memory Systems introduced a 16 kilobyte (KB) RAM solid-state drive, to be used by oil companies for seismic data acquisition. The following year, StorageTek developed the first modern type of solid-state drive.
The Sharp PC-5000, introduced in 1983, used 128 kilobyte solid-state storage cartridges, containing bubble memory. In 1984 Tallgrass Technologies Corporation had a tape back up unit of 40 MB with a solid state 20 MB unit built in. The 20 MB unit could be used instead of a hard drive.[citation needed] In September 1986, Santa Clara Systems introduced BatRam, a 4 megabyte (MB) mass storage system expandable to 20 MB using 4 MB memory modules. The package included a rechargeable battery to preserve the memory chip contents when the array was not powered. 1987 saw the entry of EMC Corporation into the SSD market, with drives introduced for the mini-computer market. However, by 1993 EMC had exited the SSD market.
Software-based RAM Disks are still used today because they are an order of magnitude faster than the fastest SSD, but they consume CPU resources and cost much more on a per GB basis.

Flash-based SSDs
In 1994, STEC, Inc. bought Cirrus Logic’s flash controller operation, allowing the company to enter the flash memory business for consumer electronic devices.
In 1995, M-Systems introduced flash-based solid-state drives. They had the advantage of not requiring batteries to maintain the data in the memory (required by the prior volatile memory systems), but were not as fast as the DRAM-based solutions. Since then, SSDs have been used successfully as HDD replacements by the military and aerospace industries, as well as for other mission-critical applications. These applications require the exceptional mean time between failures (MTBF) rates that solid-state drives achieve, by virtue of their ability to withstand extreme shock, vibration and temperature ranges.
In 1999, BiTMICRO made a number of introductions and announcements about flash-based SSDs, including an 18 GB 3.5-inch SSD. In 2007, Fusion-io announced a PCIe-based SSD with 100,000 input/output operations per second (IOPS) of performance in a single card, with capacities up to 320 gigabytes. At Cebit 2009, OCZ demonstrated a 1 terabyte (TB) flash SSD using a PCI Express ×8 interface. It achieved a maximum write speed of 654 megabytes per second (MB/s) and maximum read speed of 712 MB/s.[21] In December 2009, Micron Technology announced the world's first SSD using a 6 gigabits per second (Gbit/s) SATA interface.

Enterprise flash drives
Enterprise flash drives (EFDs) are designed for applications requiring high I/O performance (IOPS), reliability, and energy efficiency. In most cases, an EFD is an SSD with a higher set of specifications, compared to SSDs that would typically be used in notebook computers. The term was first used by EMC in January 2008, to help them identify SSD manufacturers who would provide products meeting these higher standards. There are no standards bodies who control the definition of EFDs, so any SSD manufacturer may claim to produce EFDs when they may not actually meet the requirements. Likewise, there may be other SSD manufacturers that meet the EFD requirements without being called EFDs.

What Is SSD ? 2012-04-07T02:36:00+07:00 Rating: 4.5 Diposkan Oleh: Unknown