Hard Drive Memory Lane

Chabil Ha' writes "CNET has gathered together some good old nostalgia from the photo vault. What high-tech product advances the fastest? It's probably the hard drive. The capacity doubles easily every two years and sometimes every year, faster even than the chip progress described by Moore's Law. The first drives took up storage closets. Now, a 5GB drive can fit in a phone."

Comments

Re:Why oh why???

[Dysproxia]

Linear? (FirstHDCapacity * 2^x) where x is number of years, looks a lot like exponential growth.

Re:depends on how you measure improvements

[Karma Farmer]

They can actually break the sound barrier?

No. The speed of sound at sea level is about 340 meters per second, or about 13,400 inches per second. On a 3.5" disk, that works out to about 1200 revolutions per second, or 72,000 revolutions per minute.

So, a 3.5" disk would need to spin about 10 times as fast as they do now to break the sound barrier.

Differential equation

[tepples]

Doubling every year is linear?

It's linear as in a first-order linear differential equation: dy/dt = k*y, whose solution is y = y(0)*e^(k*t).

Re:depends on how you measure improvements

[prophase_j]

It might be worth reminding everybody that the head rides a minute cushion of air as the platters whiz by below them. Take the air out and you will certainly see "werid things happen". Ever read the specs to a harddrive as far as the operating conditions go? Has a lot due with air pressure. Drives even come with holes so that they can "breath" at different altitudes and temputure. Back in the day... with my Tandy 2000 and 20 meg drive, you had to run a program telling the drive to park the head; meaning to place the head in good spot to land as the disk slows down when you turn it off. If or anyone takes upon themselves to operate a dirve in a vaccum, take pictures and/or video. I wanna see it.

J

Urban legend about magnet range

[Flying pig]

I can assure you that two magents that fit into a 5.25 inch hard drive would not collide from a foot apart horizontally. The attraction law for magnets is very roughly inverse cube (NOT inverse square, because there are two poles not one). In fact (and I tested it) the magnets from an old WD SCSI drive would come together from between one and two inches apart, and believe me that is quite a lot for magnets with very close poles. However, it is perfectly true that if these ceramic magnets are allowed to come together they can shatter.

In fact, the magnets are the most useful things in junk hard drives - they can be used for all sorts of little jobs - but as hard drives get ever lighter and more efficient the magnets get ever less useful. Old SCSI drives are the best. A standard IBM 9Gbyte drive contains two magnets with a holding capacity which would cost over $50 from the hardware shop.

Re:depends on how you measure improvements

[GuyWithLag]

The actual problem is that there is an upper limit of (relative) flow speed vs the platter, above which heavy turbulence starts. It's the same reason CD's have a max speed of about 52x or so. While both platters and R/W head are much more stiff than the CD equivalents, this does set a limit on the maximum rotational speed.

On the other hand, heat generation/dissipation is also a big problem, especially with bigger data densities, where on-disk bits are easier to flip.

Re:What about SCSI ?

[42Penguins]

http://www.newegg.com/Product/Product.asp?Item=N82 E16822116148
NewEgg has a Fujitsu 300GB SCSI drive... for $730!

SCSI drives are significantly more expensive than SATA or IDE, especially when you get into the high capacities. The makers are expanding their SCSI lines, but most individuals don't need/can't afford the big ones. If you're a big enough business or government agency, the game changes.