SSD's: What are they and when should I buy one?
What's an SSD?
SSD is an acryonym for Solid State Disk and is a name given to a new type of hard disk which differs from the older type of hard disk (rotational magnetic disks) in a very significant way. Up until the SSD's introduction, all hard disks in the industry and the vast majority in use today, use rotating magnetic platters with read/write heads that move back and forth across to read and write your data. The new SSD does away with all that and instead stores all your data on solid-state computer chips just as in a USB flash drive or the memory card in your camera.
There are three main benefits to this, the first being reliability: because there are no longer any moving parts, the disk (which stores all of your work, programs, windows, etc.) lasts a lot longer and is less subject to wear and tear. The second advantage of the SSD over it's predecessor is speed, and the third benefit is that they use less power.
How much more reliable?
It's hard to put exact figures on this, as it varies from system to system, but if we look at the manufacturer's specifications for hard disks, a common MTBF (mean time before failure) for an old rotational hard disk is anywhere from 30,000 to 50,000 hours. SSD's typically have a rating of 1.5 million hours which is an improvement of 30x or 3000%, but also equivalent to 171 years. Certainly more relaibility than would be practically useful, but compared to the old technology that's good for about 5 years, it's much nicer to be certain that your hard disk is going to last until you decide to replace it and you're not going to be stuck working from the last backup.
How much faster?
This is a tough one to answer as the person asking this question usually means "how much faster will it make my computer". There are many technical articles that go into a lot of detail about storage cost efficiency vs. relaibility, but I'll just consider the simple case of a single computer, be it a laptop or desktop for the simplicity of explaining it to the layperson. The hard disk is the slowest part of the computer, and when you're waiting for windows to start, and most of the time when the computer is stuck you can see the hard disk is very busy, trying to keep up with all the demands the computer is making of it. Most systems have a light that flashes when the disk is in use, but if yours does not, you can most often hear the hard disk clicking and churning as the computer starts if there's not a lot of background noise. From the spec sheets, the SSD delivers about 10x the speed of a rotational hard disk in terms of how quickly it can locate data on the disk but the throughput is not quite as dramatically improved. Limited testing so far, has yielded an estimated 30-50% increase in overall system perfomance.
While it's true this is not a major selling feature of the SSD, the power savings are somewhat significant and worth mentioning as it applies to battery-powered systems. As with the performance estimates in the prior section, testing is somewhat limited, but so far, increases of 25% battery life have been seen.
When should I buy?
This depends heavily on the application. The only downside of the SSD is the cost. Larger SSD's are still very costly, so if you need to store hundreds of gigabytes, SSD's are not going to be a very cost effective solution, as using multiple magentic drives in a mirrored configuration will save a lot of money while offering the same reliability and performance. But, if we look at the example of a typical windows workstation computer, on average, a system like that might only need about 20 to 80 GB of storage, and SSDs in that size category are hardly more expensive than their traditional counterparts, making them the best upgrade for your system you can get in terms of performance for your dollar.
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