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Hitachi Predicts 3D Hard Disks by Year's End
daria42 writes "Hitachi has announced that its perpendicular, or 3D, hard disks should be out by the end of 2005." From the article: "Today, hard drives record and store data in a longitudinal fashion, with the read/write heads scanning over a horizontal plane. In perpendicular recording, data bits are aligned vertically, allowing for more data to be squeezed into a finite area. Put another way, data will go from being stored on a two-dimensional XY grid to living in a three-dimensional XYZ space."
Each bit on the hard disk is represented by a small area of magnetized particles (like lots of little bar magnets).
With the longitudal system, the particles are magnetized so that the North and South are both on the surface of platter (bar magnets lie flat on the surface).
ie. <N-S> <S-N> <S-N> <N-S> <N-S>
With the perpendicular system, the particles are magnetized by a field that is perpendicular to the surface (bar magnets point up or down) ie.
^ ^ ^ ^ ^
N S S N N
| | | | |
S N N S S
v v v v v
Obviously, this has the potential for increasing storage capacity.
Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
OK, I found the article and headline a little short on hard facts, so did a quick search for a better explanation. You can find that here:s _5_23/ai_103731260
http://www.findarticles.com/p/articles/mi_m0BRZ/i
The alleged move to 3D is something of a red herring.
It appears that with current longitudinal technology, each bit is encoded by a magnet with a North-South axis that lies in the same plane as the platter itself and occupies some 100 grains of the magnetic material. The novelty here is that in perpendicular recording, the magnet is stood on end with its North-South axis perpendicular to the plane of the platter.
Apparently this theoretically leads to greater areal densities of data exceeding that of the longitudinal technology. This is where the win occurs.
In particular, what initially confused me is that we are not talking about multiple layers of data within one platter. There is still only one layer of data per side per platter, but we have achieved greater areal density of that data. Exactly what that density will be once these drives are in production is anyone's guess.
Any help?
no time, no sig
Actually, you are completely wrong. This article is pretty bad at actually explaining what Perpendicular recording is, so here it goes. Normal drives magnetize a certain area of a very thin layer of magnetic material on the surface of the platter. This means each bit has a certian area. This area has become so small that to make it any smaller would mean it would be too weak to actually be read. So the solution is to magnetize the media in the third dimension, 'into' the platter. This allows the bits to take up less space and still be strong enough to be read. Actually being able to 'stack' bits like you think would REALLY increase storage capacity! And Thers even a technology to come in after Perpindicular recording has ran out of steam called laser assisted recording, where a very weak lazer heats up a tiny spot on the drive, making it much easier to record. But again the spots are so small that they are difficult to read. Personally I hope that the IBM Millipede tech matures to the point where it can replace hard drives. Or maybe a rewritable version of those Holographic discs
The short answer is that it'll work, but the reason is that in the meantime we've taken an agnostic approach to accessing drive contents.
A long time ago, in a galaxy far away, we had MFM and RLL drives which (A) required the controller to have a pretty intimate knowledge of a drive's internal workings, and (B) an access scheme that again was tightly coupled to the drive's geometry. It was in fact an addressing where you had to explicitly state the track, sector and head. So if you moved to some other scheme (e.g., adding a 4'th parameter: depth) it would fall flat on its face.
In the meantime, though, technology got smarter. Both problems got solved as follows:
A) IDE (Integrated Drive Electronics).
The industry basically moved away from having dumb drives and a controller that needs to know the exact internal workings of the drive. It took a lot of hint from SCSI. Nowadays the real controller is on the HDD itself, and the "IDE controller" on the mobo is merely a bridge to the specialized bus to commnicate with the real controller.
That's why nowadays you can have CD-ROMS, DVD-burners, etc, on an ATA ribbon. Or why you can have cache on the drives nowadays. Or why you don't have to buy a new motherboard each time a HDD vendor comes up with a new encoding.
So the short story is that as long as the drive comes with an ATA or SATA compatible controller in it, it will work.
B) LBA (Logical Block Addressing)
The addressing scheme also got more agnostic. We no longer tell the drive the exact track-sector-head coordinates. We just tell it "give me the 1075'th sector" and let the drive figure out for itself where that sector is. (That's another point where IDE comes in handy.)
So the short story is: as long as the sectors can be numbered, any geometry will work. Adding an extra dimension just means you'll have to number the sectors differently. But as long as you can number them, you're all set.
(Of course, this is assuming your drive doesn't end up bigger than 144 PETAbytes, which is the limit for 48 bit LBA with 512 byte sectors. If it's more than that, well, we'll have to switch to using more bits.)
A polar bear is a cartesian bear after a coordinate transform.
So
distance - - - - - - - - >
N S . S N . S N . N S
is now shorter
- - - - - - >
N S S N
S N N S
(Lameness filter encountered. Post aborted!
Reason: Don't use so many caps. It's like YELLING.)
The pick-up head has inertia due to the mass of a hefty ceramic magnet and several hundred turns of copper wire. There's a counterweight balancing it so that there is only a couple of grammes' weight bearing down on the record, but it has a hell of a lot of inertia compared to the steel shank of the stylus, which is attached to a very flexible coupling. So when the groove pulls the needle to the left, the needle moves left but doesn't take the whole pick-up head with it; the magnetic flux lines change and induce a current in the coils. The preamplifier has a relatively high input impedance, so the needle isn't actually doing much work generating electricity. Otherwise it would feel stiffer.
Side-to-side motion is the sum of left and right signals. Up-and-down motion is the difference. By using four coils, not two, and pulling cunning stunts with the wiring, you can create a sum and difference of the sum and difference signals without resorting to op-amps. Which, of course, gives you {more or less} the original signals
Je fume. Tu fumes. Nous fûmes!
When the data density of hard drives increases the data transfer speed increases. .006 sec to spin that track past the read/write head (that's 10,000 rpm). This means that the data transfer rate from the track is about 1/6 MB/sec.
Imagine one of the tracks on the platter. Suppose that the track contains 1KB. Further suppose that it takes
Now, double the density of data on the platter. This would make 2KB in the same track, increasing the transfer rate to about 1/3 MB/sec.
(Historically the read/write sensitivity, time required to convert the signal to true binary for the computer, and distance to controller card have been speed bottlenecks. However, I think that the current bottleneck is the data transfer rate from the platter to the read/write head.)
Exam 4/C again. Maybe I'll do better this time.
Sure, there are companies like IBM who put more money in to R&D than the GDP of a small Central American country, and they've been prototyping holographic drives and such for years. Yes, there were press releases, but they never said they were going to be releasing by year end.
Besides, this isn't some pie-in-the-sky technology, it's turning data stored on its side to data stored on its end...if they already having working prototypes in the field that are mass produced, why couldn't they put these on shelves by year end? I mean, it's not a new product, it'll just be the hard drive sizes we've been expecting for a while. Wouldn't surprise me if they started with 650GB in November/December and ramp up over a few years to 1.5-2.0 TB.
Oh, and also note that this isn't some no-name company (i.e. Bit Boys, Infinium) coming out with this release, it's one of the market leaders in hard drive technology (IIRC, Hitachi was the first to produce those CF-form-factor micro drives, even though they were IBM branded).
I don't think believing this makes someone a sucker; I think you're being a bit too cynical. But then again, any sucker would say that, wouldn't they?