About Solid State Drives
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Solid state technology has been around for many years now. In modern times, a solid state drive (SSD), is being used extensively in portable computing devices.
Solid state in electronics refers to the circuitry that is made completely with the help of semiconductors. In the earlier days, solid state electronics referred to the transistor radio circuits which used semiconductors in place of vacuum tubes.
But today, much of the electronics in most equipment is built with semiconductors and integrated chips.
Also known by names such as solid state disk or electronic disk, SSDs provide primary storage constructed with the help of semiconductors, unlike HDDs that use magnetic media. A solid-state-drive is usually placed on the inside of an electronic equipment instead of the magnetic media. Flash drives are usually connected to the device through external USB ports.
Hybrid Drives are available in the market that sport features of both the SSD and the HDD. They are made as single units. They have a bigger-sized HDD placed alongside a smaller Solid State Drive for faster access. They are reasonably cheap.
The SSDs and flash drives use non-volatile NAND memory chips that retain information even when not supplied with power. However, there also exist SSDs that use volatile DRAM memory. They are typically used for applications that do not need to retain the data after loss of power. Alternately, they can use other external sources of power or batteries for data retention. They provide faster data access and improve performance of frequently accessed files. They are costlier than flash memory-based chips.
Any SSDs main components include the controller and the memory that stores the data. The controller consists of the electronics that connect the memory units to the host computer. Their operations include error correction, read and write caching, garbage collection, etc. The smaller components of the SSD include the host interface, optional battery for maintenance of data integrity, a small amount of DRAM cache memory, etc. The performance of the SSD can be improved by placing a number of NAND flash chips in parallel. Flash memory chips are packaged in typical form factors such as 1.8-, 2.5-, and 3.5-inch sizes to remain compact.
The advantages of an SSD compared to the traditional HDD are as follows:
- The start-up time is almost instantaneous for an SSD as opposed to a HDD where it may take several seconds because of mechanical movements that are involved.
- Random access time is as low as 0.1 ms, whereas in a HDD it may range from 5 to 10 ms because of the rotational delay and seek time.
- The read time is also low for an SSD as the drive works by reading data directly. In HDDs time is taken for the mechanical components to realign for every read.
- Power usage in an SSD is lower. There are no motorized drives as in a HDD. Therefore less energy is required.
- Solid State Drives are more reliable and hence find a place in most portable electronic equipment. HDDs are sensitive to physical movements and impacts from knocks owing to the mechanical parts.
- SSDs allow for silent operation as there are no moving parts.
However, it is also interesting to note that the solid state drive is not used in all PCs because of the cost involved and the capacity offered. All this may change in the near future when more companies manufacture SSDs of larger capacities at lower costs.
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