Solid State Drive

For as long as computers have been around, hard drives have been used to store large amounts of data. Every year, new models are released that have even greater capacities than previous models. Until recently, there was no viable alternative to the hard drive, but the solid state drive (SSD) is shaping up as its replacement. By changing from mechanical parts to flash memory chips, many of the problems that affected hard drives have been avoided, such noise and high latency. For notebook computers, these new drives are useful for reducing weight, saving power, and extending battery life. However, cost factors will ensure that hard drives remain on desktop computers for some time to come.

A solid state drive is similar to a memory card or a USB flash drive but with a much larger capacity. On the outside, it looks like a hard drive and has the same screw holes along its edges. This allows it to be placed in the same bays in a computer case that a hard drive would normally go. It also has a socket on the back for a SATA cable. Things are very different on the inside, however. The only internal part is a large circuit board with an array of memory chips mounted on it. One type of solid state drive uses flash memory, while the other type uses DRAM memory. Unlike the chips used on sticks of computer memory, these do not require constant power to maintain their data.

A hard drive contains several large parts which move at very high speed. In the center of the drive is a spindle that has a number of metal disks, called platters. As the platters spin, actuator arms swings back and forth just above their surfaces. Magnetic heads on the tips of the arms read data from the platters and also write data to them. Hard drives produce a small amount of noise and heat because of these moving parts and the friction in their bearings. The inertia of the moving parts also cause a time delay, called latency, between when the computer sends a command and when the hard drive responds.

The lack of moving parts in a solid state drive is the main reason why it has so many advantages over a hard drive. These include silent operation, lower latency, better reliability, and lower power usage. Data transfer happens much faster when there are no platters to spin or arms to move, which gives a solid state drive a much lower latency. It also has a greater reliability because there is less chance of it being damaged internally. If a hard drive is knocked while it is running, the magnetic heads can touch the platters and cause data loss or even permanent damage. Models that use flash memory require less power and generate less heat, but models that use DRAM memory use even more power than a hard drive.

Despite its many advantages, a solid state drive is not a perfect alternative to a hard drive. It takes much longer to write data that to read it. The cost per unit of storage is as much as five times higher compared to a hard drive. While that cost will come down in the future, hard drives will remain the most economical means of data storage for many years. A solid state drive that uses flash memory chips has a large but limited number of write cycles, meaning that it will eventually stop accepting new data. Fortunately, data can still be read after this happens, unlike a hard drive which often loses all its data when it fails.

There can be no doubt that the days of the hard drive are numbered, but it is difficult to know how long it will be before there is a solid state drive in every computer. Microsoft seem to think that this time is not far off. While previous versions of their Windows operating system were designed for the hard drive, the upcoming Windows 7 is designed for the solid state drive. The increasing popularity of mobile computing is another reason why more of these drives will be appearing in the future. In the mean time, hybrid drives that combine a regular hard drive with a large buffer of memory chips will provide a bridge to that future.

This Solid State Drive Review is Written/Updated on Nov 9th, 2009 and filed under Computer Hardware. Both comments and pings are currently closed.

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