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."

Comments

Centrifugal force

[Xocet_00]

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.

He just gave a talk on this...

[Rhys]

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.

Re:Cringely's time machine

[itwerx]

Forgot to mention, the reason film isn't used is the coefficient of expansion. There's no temperature regulation in drives (yet) and there isn't a film material in existence that doesn't expand and contract with the temperature. That's actually one of the reasons glass was introduced awhile back, data densities were getting so high that even the rigid metal platters were moving enough to become a factor.

Re:Speed control

[Svartalf]

Uhm... That's NOT quite true... Cut the power off, the disc eventually stops spinning because of friction, etc.

You need to supply a constant input of angular momentum to keep the discs spinning. Spinning a
smaller mass will ALWAYS mean a lower power input, from start to finish and everything in betweeen.

Re:The Gyroscope Effect

[drakaan]

two words from the article: "air cushion" apply deductive reasoning as to how much more those two words matter when coupled with a flexible platter. There's actually plenty to read in the article, and I have lots of specific questions, but shock scenarios were something that cringley specifically addressed (like not having to park the heads or use "uh-oh" sensors to detect imminent shock, etc).

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.