SSD is a term coined a long time ago for a device that acts like a hard drive but with no moving parts. According to Wikipedia, they've been in use since about 1970. I don't know how the term "Solid State" came to refer to this, but I remember televisions and electronics when I was very young that had the term emblazoned on them like a badge of excellence. I'd look at it and imagine perhaps liquid or gaseous TV sets. SSDs are being proposed again as a main storage device for computers with a couple recent news articles. BetaNews published a story last month about a product announcement from Samsung. Now Slashdot points to an article speculating the Samsung SSD might show up in Apple products.
Read on for my observations
The idea has come up before, but hard drive sizes and their price to performance ratio have always beaten out solid state. Right now flash drives are finding widespread use in cameras, mp3 players, PDAs and piles of other places. It's still cost-prohibitive for the average consumer to hook up enough flash memory cards or thumb drives to make a substitute for the average hard drive, but someone over at Ars Technica did manage to test a few of them out in a RAID configuration last year. As of right now, you could go over to Amazon and buy the cheapest flash memory you can find and try a set up like that. It's going to cost you dearly to compare to the current minimum of about 80GB for a decent system.
I find this stuff interesting because it's something I've been hoping to see for a long, long time. It's the technical purist in me, I just don't like the idea of a mechanical device that relies on all that slow physical motion being of such central importance to my computer. It seems like a huge point of failure. I don't have facts to back that one up, but mechanical devices seem much more likely to fail than electronic ones. That could be one marketing angle I suppose. The real advantages of solid state memory (flash or otherwise) are clear and factual though:
No head hitting the platter a million times a second. The term "disk thrash" would have to be explained to new programmers and they wouldn't be able to identify viscerally with that awful scratching noise. I once heard a story that William Gibson called his Apple dealer the first time he heard the hard drive spin up. There was nothing wrong with it, but the inventor of the term 'cyberspace' didn't realize his first computer would be so noisy (I remember hearing him relate that in an interview, but can't find a reference).
The motion and inertia of rotating platters is mostly noticeable in laptops or external drives, but vibration causes other things in a desktop case to make more noise.
Less electrical noise
One more way to simplify motherboard design. Less inductive load on the power supply because there won't be a motor to drive. Maybe this would remove the need for the 12V line?
Lower power consumption
Transistors draw less power than motors. Some transistor technologies only draw power when they're switching states. Flash, of course, is non-volatile and doesn't need to be powered at all when it's not being accessed. A conventional hard drive, on the other hand, has to keep all it's bits spinning if you're going to use it at all.
Going along with that last point, reducing power consumption could mean reducing battery needs and that takes substantial weight out of laptop and portable computers. Now that's a health benefit for me. I love my notebook, but it weighs approximately 2.4 tonnes. Anything to save my back.
Really, the implications of widespread adoption of SSDs would be pretty incredible. It would be feasible to move the permanent storage on to the motherboard (in some cases, not all), integrating the hard drive in just like the video card and sound card can be. Single board computers are definitely around today and have been for a long time, but this would make them very much like any other PC, instead of a specialized case. It could incite another round of price cuts to computers which would in turn broaden the market. That has a positive feedback effect and prices could drop for everyone.
If the solid state drive ever becomes more common than the rotating media drive, the interfaces (SATA and SCSI) could be revised and perhaps simplified to reflect the simpler interface to flash. It might or might not be much simpler, I suppose, since flash memory has it's own idiosyncrasies. At least they're faster idiosyncrasies than magnetic media.
It hasn't managed to happen in the past, but maybe this time there's enough cheap flash memory out there that solid state drives can finally compete in the general consumer market. Samsung's explanation of prices dropping 40% last year doesn't convince me, but their leading position as flash memory producers makes me hopeful.
By the way, I'm building up another tech news page to keep me informed. If you're interested, take a look.