The End Of The Road For Magnetic Hard Drives?

Phase Shifter wrote to us about the limits of conventional hard drives, which Scientific American is discussing. The article talks about the history of hard drives, and why sometime soon, due to the limitations of the superparamagnetic effect, we will need to find a new storage type. It's a cool background read on hard drives and what goes into them.

Comments

Same old same old...

[dillon_rinker]

A Brief History of Hard Drives
(a la Book-A-Minute).

Scientists: OH NO! Hard drives can't get any better!

Engineers: Wait! Your science is WRONG! (Writes some new equations).

Computer industry: You have SAVED us!

Geeks: YAY!

Hard Drives, Modems, Palimsets and other trivia

[jd]

Once upon a time, it was said that modems could never exceed 9,600 bps, as the phone lines couldn't cope with higher than 9,600 baud.

Then, one day, someone realised that - hey! If you throw away the assumption that baud == bps, you can actually drive up speeds to 56Kb/s!

Then, as modems went up in speed, the same engineers moaned and groaned. The 56Kb/s limit was near, and without a total rewiring of the phone network, an act of Congress in the US (an act of God elsewhere in the world), and more money than anyone had, the 56K barrier would never be breached! Calamity!

Then, one day, another bright spark realised that if you had modems at the junctions, you could shove REALLY high-speeds down the wires without either Congress -or- God having to do anything. (Much to the relief of both.)

The Doomsday Crowd, defeated once more, lurked on the fringes. Until, one day, redemption! Hard Disks can't pass a certain density!

This, of course, is as bogus as all the other claims. If it's possible to read the past ten writes on a given sector, then you can you can increase the density of the disk by AT LEAST an order of magnitude. You just have to remember to read/write all ten layers at one time, and you're fine.

Then, of course, there's no rule which says you have to use 2-state logic. It's easy, but it's not mandatory. Magnetic fields can have any orientation and any strength. So long as the maximum strength isn't so high that you get bleeding, you're fine. Recognise 256 possible states (using any combination you like of orientation and strength), and you've "encoded" a single byte into a bit - a x8 gain in disk capacity.

Combine the two, and you've increased the capacity by over 80 times! This can be increased still further, by increasing your ability to scan over-written layers, and by increasing your ability to distinguish magnitudes and orientations. You have two degrees of freedom for rotating the magnetic field, which means that by doubling the ability to distinguish, you quadrouple the number of possibilities available.

The scientists may be correct about the density, but the density is NOT the only variable open to hard drive manufacturers. In the future, it may become one of the least significant, as others are explored.