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Cringely's Shameless Self-Promotion
wild_berry writes "The latest edition of Bob Cringely's column at pbs.org, entitled Shameless Self-Promotion: Bob's Disk Drive is up. He's talking about replacing the glass or metal platters in present hard disk drives with foil platters in order to save energy." From the article: "The materials cost more but we use so much less of it (the disk is so incredibly thin) that the total material cost is substantially less. This 'floppy' material has the same kind of magnetic coatings used on standard disk drives and our drives live on the same technology growth curve as those others. The way we obtain greater storage density is simply by putting more platters in a drive (say 12-15 instead of 4-5 in an enterprise 3.5-inch drive) because they are much thinner and can be stacked closer together. The only parts of the drive that are significantly different are the platters and the heads and the heads vary only in having an extra slot."
Get out the tin foil...umm.. okay, it's alrealdy in there
I should read the FA, but what's to stop his platters from flopping all over the place?
The
And what do these thinner materials and more closely-spaced heads do for the MTBF and error rate in such drives?
That's quite a bold claim! If his claims are accurate, then we may be looking at the future of hard disk drives. Micro-disk drives would become the latest hotness, and Flash would disappear entirely from our memory. IF the technology works, that is.
Time and speculative investors will tell if it's really everything it's cracked up to be. I certainly hope it is, but extraordinary claims require extraordinary evidence.
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Ideally, the disks would be spinning so quickly that the outward force would keep them almost perfectly flat. Assuming the disks were very smooth and the internal atmosphere of the drive is gas-only (no dust - a safe assumption) there would hopefully be very little turbulence within the drive to cause fluctuations in the flatness of each platter.
In my lab we coat floppy materials (like plastic) in a spin coater at several thousand RPM. At that speed the disk may aswell be rigid.
At the UIUC Reflections|Projects ACM conference. It was actually a fairly interesting talk (http://www.acm.uiuc.edu/conference/2006/webcast.p hp) about the same topic, maybe a little more in-depth than the article. At least more pretty pictures than the article.
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Cringley must be old enough to remember Bernoulli disks. (They used a plastic film but same concept applies.)
Speed control of the rotating disk is going to be harder if the disk has less mass. You basically loose a nice dampener that you had in the system.
The only real power savings would come during spin-up. Once the disk is spinning, there's no additional power used to rotate a heavy vs. a light flywheel. (Well, a little bit because of increased bearing friction, but it's probably negligible.)
Finally, if you lighten up the parts in a hard drive, most companies are just going to use the energy savings to drive the parts FASTER.
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*I Am Not A Disk Drive Engineer But I Am A Mechanical Engineer
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The real savings comes from the fact that the coating/finishing of the platters can be done on a big roll of foil and the platters can then be just stamped out. Standard platters must be finished individually.
I don't read your sig. Why are you reading mine?
I seem to recall in the late 80's and through the 90's a removable cartridge drive system known as Bernoulli drives. They had "floppy" media (mylar, though, not foil), The drive would spin up the disk, then insert the heads, which were like hard drive heads - floating over the surface rather than the more standard pressed against the surface (a la Zip/Floppy drives).
Ah, Wikipedia - http://en.wikipedia.org/wiki/Bernoulli_drive
Basically, this drive is similar, just in a self-contained format rather than a removable cartridge solution?
Though, bumping the drive while spinning could do a lot of damage from precession of the platters causing the material to warp. Fast spinning disks are miniature gyroscopes.
In particular, I'd like to see evidence for the following claims:
I'd sure like to see the assumptions and numbers underlying that equation. Gee, Cringe, which do you think costs more: The raw platters themselves, or the read/write heads? I would say the latter. So you're going to drop the costs of hard drives by doubling the most expensive component? Huh? Sorry, I'm not buying this at all. You don't think a non-cleanroom enclosure is going to result in data loss on the platters themselves? Even if you're not getting particles during the read/write phase itself, you're getting them on the platter. I'm not buying the logic here. Sorry, I'm not buying this at all. Until the advent of true Drexlarian nanotechnology, I doubt you're going to see a mechanical action (you still have to move the eread/write heads) beat an eletronic one (reading from Flash).I'm not saying that the technology Cringely talks about is impossible, I'm saying: A.) There seem to be a lot of unwarrented assumptions underlying his logic, and B.) Implementation always has unforeseen hurldes and obstacles that will make these drives seem like far less of a slam-dunk vs. current technology (or more specifically, where regular drive technology will be 18 months from now) than it appears.
Finally, once it is ready, I'd like to see real-world tests for speed/electrical consumption metrics with existing technology. There might indeed be some savings, but I seriously doubt they are as dramatic as Cringely claims.
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The heads only have to touch the film a few times before the emulsion is history.
We use glass because it's dimensionally stable, easy to make extremely flat, and it's about as rigid as you could want it to be, regardless of whether the disk is spun up or not.
-jcr
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Actually, modern revolving doors have a breakaway feature so traffic can go straight through in emergencies. If you try hard enough it is quite possible to slam one.
Just thought you would like to know.
You never really know how close to the edge you can go until you fall off.
All hard drives do that. In fact, if you suddenly cut off a normal hard drives power, the momentum of the disk will keep it spinning long enough to maintain said cushion of air while the head returns to the parking position.
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The platters have (per platter) a much smaller edge, so they're going to get less friction from the air. Less friction means less heat AND less power required to keep the disk spinning at the same velocity. The area isn't that big compared to the surface of the disk, but I'd guess (assuming the heads were at the outer tracks of the disk) that the air near the spindle spins with the disks and probably causes very little if any friction, so the majority source of air friction is going to be the edge (where it moves air around the "interesting" interior shape of the enclosure).
In his talk I referenced above, he specifically stated that they were using smaller/lower power motors because they didn't need as much power as a conventional disk. Also remember that conventional disk motors may have to be "overspecced" to be able to spin the disks up to speed in a reasonable amount of time, and that may make them less efficient when they're just trying to maintain speed rather than spin up. You'd have to ask an EE on that one though, 'cuz I'm not. Just another stab that occurs to me for why it may cost a lot less power.
He also referenced making higher-RPM drives than current methods. I want to say 30k sticks in my head, but I'm not sure on that you'd have to watch the talk to verify my tylenol cold muddled memory.
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The article is admittedly short on specifics, but I imagine they'll be forthcoming, since he also mentioned that we'd actually be seeing the drives from numerous manufacturers next year.
If they managed to prove the tech to drive manufacturers, I'd imagine the dimensional stability of glass didn't trump the tech they're introducing.
"Murphy was an optimist" - O'Toole's commentary on Murphy's Law
Not sure who the multiple HDD vendors are that will be introducing it next year, but I'm sure they asked a lot of questions about that, too.
"Murphy was an optimist" - O'Toole's commentary on Murphy's Law
You can assume whatever you want but the article repeatedly mentions that they can be spun down, and that their spin-up time is less than a half a second (at least for small drives) to be read. Making assumptions when the FA is there for you to R makes an ass out of you, and umption.
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Now imagine what happens if you tilt the drive.
The hub now has to transfer a force rectangular to the foil-plattern's surface - fast - to tilt the rotating plattern inside the drive.
But the foil-plattern want to stay where they are (think bicycle wheel)
A foil doesn't provide much resistance rectangular to it's surface. The process is called "folding" if done exactly or "crumpling and head crashing" if done in a foil-platter-drive. Maybe it would even be called "cringling" then?
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Sure traditional Hard Drive manufacturers may be in jeopardy if they don't license this technology but don't discard flash just yet.
First thing flash has over this technology is *proven* reliability. This new technology can't buy that for money nor love.
Second thing is that this technology has *nothing* over flash (except maybe extreme temperatures, but special flash chips exist too). Performance is not said to be better than flash (you can't beet nanoseconds to access data in flash).
The only thing it has over flash at the moment is a cheaper price. Have you seen flash price trends over the last two years? I would say that it roughly obeys an inverse Moore Law (where prices for a same capacity are halfed every 18 months).
Flash chips are nothing but plastic and silicium. If Sandisk our however started feeling some heat from this new technology they could *ALWAYS* lower the price, hoping to make it up in volume.
At the moment flash manufacturers are at max capacity and are structuring their prices to maximise profit IN THE CURRENT MARKET CONDITIONS. If a new competitor comes out with a ground breaking technology they will find a new price point to maximise their profit then.
Flash, inlike hard drives cost almost nothing to produce, their marginal cost is virually pennies, unlike tens of dollars for HDs. They currently support investment costs and high margins, but in a differnet market configuration they could outprice these new disks and ramp up production.
Flash is the future, its already here but the chip companies have no incentive to make it any more affordable than it currently is, they are milking us just like OPEC does with oil.
If somebody invents tomorrow a car that recharges in 3 mins and has 500 miles range and same performance and price as regular cars, the oil barrel will drop to $15 overnight, it's the same thing.
It's all about supply, demand and marginal costs.
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Another way to think about it is:
How much energy did you need to keep 1 TB of data online in 1980?
How much does it take today?
I would say the disk drive mfgs. have done their part.
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>The platters have (per platter) a much smaller edge, so they're going to get less friction from the air.
i f
Not failed physics... this is a flawed analysis.
There are a few different types of drag (I am an aerospace engineer). The relevant one in this case is caused by the surface of the platter, not the edge. Remember, the edge is really acting as if it were stationary - it's not moving the disc laterally thru the air, so the edge is irrelevant. Instead, the disk surface moving past the air drags some of the air with it - this is sometimes referred to as surface drag, or skin friction. No matter how smooth the surface is, moving it thru a "fluid" (such as air) causes shear in the fluid - the fluid closest to the surface is motionless, and the speed builds up as you move out away from the skin. This is called a "boundary layer". This layer can be smooth-flowing ("laminar flow") or rough (turbulent). Smoother skin means laminar flow. But there's STILL drag, no matter how smooth the surface.
Here's a good illustration: http://wright.nasa.gov/airplane/Images/boundlay.g
So making thinner disks and using more of them means MORE drag, not less.
Actually in this case, however, the motor can be sized DOWN, despite higher operating drag, because the largest power usage comes from spinning up the disc package - and a set of lighter disks will require less power to spin up. Very little power is actually used to keep it spinning, despite the drag.
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The disk is very floppy. The metal center is the only rigid part. The floppy plastic of which the disk is composed does not flop because it is too small, measuring only 1 3/16 of an inch from the metal hub.
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If I'm reading the article correctly, the claim seems to be that the lighter platters will save energy?
How?
With my primitive understanding of physics, the power required to keep something at constant velocity is basically the sum of the parasitic losses (in this case, aerodynamic and frictional losses). Changing the weight of the platter does not have much impact on energy consumption *except* for periods of acceleration (e.g. - the first couple of seconds during power-on).
Has my logic failed me here? How do the lighter platters save energy in a constant velocity system?
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