Solid-State Drives
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201751 Solidstate drive Wikipedia Solidstate drive From Wikipedia, the free encyclopedia A solidstate drive (SSD, also known as a solidstate disk[1][2][3]) is a solidstate storage device that uses integrated circuit assemblies as memory to store data persistently. SSD technology primarily uses electronic interfaces compatible with traditional block input/output (I/O) hard disk drives (HDDs), which permit simple replacements in common applications.[4] New I/O interfaces like SATA Express and M.2 have been designed to address specific requirements of the SSD technology. A 2.5inch SSD, often found in SSDs have no moving mechanical components. This distinguishes them personal computers from traditional electromechanical magnetic disks such as hard disk drives (HDDs) or floppy disks, which contain spinning disks and movable read/write heads.[5] Compared with electromechanical disks, SSDs are typically more resistant to physical shock, run silently, and have lower access time and lower latency.[6] However, while the price of SSDs has continued to decline over time (24 cents per gb as of 2017),[7][8] consumergrade SSDs are (as of 2017) still roughly four A rackmount SSD storage appliance based on DDR SDRAM times more expensive per unit of storage than consumergrade HDDs.[9] As of 2015, most SSDs use MLC NANDbased flash memory, which is a type of nonvolatile memory that retains data when power is lost. For applications requiring fast access but not necessarily data persistence after power loss, SSDs may be constructed from randomaccess memory (RAM). Such devices may employ batteries as integrated power sources to retain data for a certain amount of time after external power is lost.[4] Hybrid drives or solidstate hybrid drives (SSHDs) combine the features A PCIattached IO Accelerator SSD of SSDs and HDDs in the same unit, containing a large hard disk drive and an SSD cache to improve performance of frequently accessed data.[10][11][12] Contents 1 Development and history 1.1 Early SSDs using RAM and similar technology 1.2 Flashbased SSDs A PCIExpress, DRAM and 1.3 Enterprise flash drives 2 Architecture and function NANDbased SSD that uses an 2.1 Controller external power supply to effectively 2.2 Memory make the DRAM nonvolatile 2.2.1 Flashmemorybased 2.2.2 DRAMbased 2.2.3 Other 2.3 Cache or buffer 2.4 Battery or supercapacitor 2.5 Host interface 3 Configurations https://en.wikipedia.org/wiki/Solidstate_drive 1/27 201751 Solidstate drive Wikipedia 3.1 Standard HDD form factors 3.2 Standard card form factors 3.3 Diskonamodule form factors 3.4 Box form factors 3.5 Bareboard form factors 3.6 Ball grid array form factors 4 Comparison with other technologies An mSATA SSD with an external 4.1 Hard disk drives 4.2 Memory cards enclosure 5 Applications 5.1 Hard drives caching 6 Wear leveling 7 Data recovery and secure deletion 8 Suitable file systems 8.1 Linux 8.1.1 Performance considerations 8.2 OS X 8.3 Microsoft Windows 8.3.1 Windows 7 and later 8.3.2 Windows Vista 8.4 ZFS 8.5 FreeBSD 8.6 Swap partitions 9 Standardization organizations 10 Commercialization 10.1 Availability 10.2 Quality and performance 10.3 Sales 11 See also 12 References 13 Further reading 14 External links Development and history Early SSDs using RAM and similar technology SSDs had origins in the 1950s with two similar technologies: magnetic core memory and charged capacitor readonly storage (CCROS).[13][14] These auxiliary memory units (as contemporaries called them) emerged during the era of vacuumtube computers, though their use ceased with the introduction of cheaper drum storage units.[15] Later, in the 1970s and 1980s, SSDs were implemented in semiconductor memory for early supercomputers of IBM, Amdahl, and Cray,[16] but they were seldom used because of their prohibitively high price. In the late 1970s, General Instruments produced an electrically alterable ROM (EAROM) which operated somewhat like the later NAND flash memory. Unfortunately, a tenyear life was not achievable and many companies abandoned the technology.[17] In 1976, Dataram started selling a product called Bulk Core, which provided up to 2 MB of solid state storage compatible with Digital Equipment Corporation (DEC) and Data General (DG) computers.[18] In 1978, Texas Memory Systems introduced a 16 kilobyte RAM solidstate drive to be used by oil companies for seismic data acquisition.[17] The following year, StorageTek developed the first RAM solid state drive.[19] https://en.wikipedia.org/wiki/Solidstate_drive 2/27 201751 Solidstate drive Wikipedia The Sharp PC5000, introduced in 1983, used 128kilobyte solidstate storage cartridges containing bubble memory.[20] In 1984, Tallgrass Technologies Corporation had a tape backup 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.[21] In September 1986, Santa Clara Systems introduced BatRam, a 4 megabyte 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.[22] 1987 saw the entry of EMC Corporation (EMC) into the SSD market, with drives introduced for the minicomputer market. However, by 1993, EMC had exited the SSD market.[17][23] Softwarebased RAM disks remain in use as of 2016 because they are an order of magnitude faster than other technology, though they consume CPU resources and cost much more on a perGB basis.[24] Flashbased SSDs In 1989, the Psion MC 400 laptop included four slots for removable storage in the form of flashbased "solid state disk" cards, using the same type of flash memory cards as used by the Psion Series 3.[25] The flash modules did have the limitation of needing to be reformatted entirely to reclaim space from deleted or modified files; old versions of files which were deleted or modified continued to take up space until the module was formatted. In 1991, SanDisk Corporation created a 20 MB solid state drive (SSD) which sold for around $1,000. In 1994, STEC, Inc. bought Cirrus Logic's flash controller operation, allowing the company to enter the flash memory business for consumer electronic devices.[26] In 1995, MSystems introduced flashbased solidstate drives.[27] They had the advantage of not requiring batteries to maintain the data in the memory (required by the earlier volatile memory systems), but were not as fast as the DRAMbased solutions.[28] Since then, SSDs have been used successfully as HDD replacements by the military and aerospace industries, as well as for other missioncritical applications. These applications require the exceptional mean time between failures (MTBF) rates that solidstate drives achieve, by virtue of their ability to withstand extreme shock, vibration and temperature ranges.[29] In 1999, BiTMICRO made a number of introductions and announcements about flashbased SSDs, including an 18 GB 3.5inch SSD.[30] In 2007, Fusionio announced a PCIebased SSD with 100,000 input/output operations per second (IOPS) of performance in a single card, with capacities up to 320 gigabytes.[31] At Cebit 2009, OCZ Technology 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.[32] In December 2009, Micron Technology announced an SSD using a 6 gigabits per second (Gbit/s) SATA interface.[33] Enterprise flash drives Enterprise flash drives (EFDs) are designed for applications requiring high I/O performance (IOPS), reliability, energy efficiency and, more recently, consistent performance. In most cases, an EFD is an SSD with a higher set of specifications, compared with 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 https://en.wikipedia.org/wiki/Solidstate_drive 3/27 201751 Solidstate drive Wikipedia meeting these higher standards.[34] There are no standards bodies who control the definition of EFDs, so any SSD manufacturer may claim to produce EFDs when in fact the product may not actually meet any particular requirements.[35] An example is the Intel DC S3700 series of drives, introduced in the fourth quarter of 2012, which focuses on achieving consistent performance, an area that had previously not received much attention but which Intel claimed was important for the enterprise market. In particular, Intel claims that, at a steady state, the S3700 drives would not vary their IOPS by more than 10–15%, and that 99.9% of all 4 KB random I/Os are serviced in less than 500 µs.[36] Another example is the Toshiba PX02SS enterprise SSD series, announced in 2016, which is optimized for use in server and storage platforms requiring high endurance from writeintensive applications such as write caching, I/O acceleration and online transaction processing (OLTP). The PX02SS series uses 12 Gbit/s SAS interface, featuring MLC NAND flash Top and bottom views of a 2.5 memory and achieving random write speeds of up to 42,000 IOPS, random inch 100 GB SATA 3.0 (6 Gbit/s) read speeds of up to 130,000 IOPS, and endurance rating of 30 drive model of the Intel DC S3700 series writes per day (DWPD).[37] Architecture and function The key components of an SSD are the controller and the memory to store the data.