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LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
PostgreSQL 9.3 beta: Federated databases and more
LWN.net Weekly Edition for May 9, 2013
(Nearly) full tickless operation in 3.10
What's an order of magnitude among friends?
Posted Jan 31, 2013 17:05 UTC (Thu) by drag (subscriber, #31333)
Going from that I figure a 72k rpm disk would make a nice sharp ZZzzz-ng noise as it explodes and shrapnel zips past (hopefully) your head.
Posted Jan 31, 2013 20:51 UTC (Thu) by rgmoore (✭ supporter ✭, #75)
Bullets are not known for their rugged construction; in many cases it's considered desirable if the bullet breaks up on impact so it can dump its kinetic energy more efficiently. Devices that are intended to operate at 72K RPM and above are certainly practical. Many of the machines I work with have turbomolecular pumps that operate in that speed range, and their diameter is larger than a disk drive so the force is larger as well. Similarly, ultracentrifuges operate at substantially higher speed than that- they can go above 100K RPM- without exploding. The thing they have in common is that they operate under vacuum to minimize friction. I suspect an ultra-high speed disk drive would need to do the same. As long as the vacuum is maintained, they would probably be pretty quiet. The motors would tend to give off a ~1200 Hz (e.g. 72K cycle per minute) whine.
Posted Feb 2, 2013 18:25 UTC (Sat) by nix (subscriber, #2304)
The motors would tend to give off a ~1200 Hz (e.g. 72K cycle per minute) whine.
Posted Feb 2, 2013 18:27 UTC (Sat) by Tet (subscriber, #5433)
You don't even need that. Most turbos routinely spin in excess of 100K RPM without needing a vacuum, and the Honda CX-500 had a turbo that spun at 200K RPM. Pretty insane, but it worked.
Posted Feb 8, 2013 0:16 UTC (Fri) by dfsmith (guest, #20302)
Posted Feb 13, 2013 22:17 UTC (Wed) by Lennie (subscriber, #49641)
So this isn't an alien concept to producers of harddisks.
Posted Feb 14, 2013 17:58 UTC (Thu) by nix (subscriber, #2304)
Posted Feb 14, 2013 19:49 UTC (Thu) by Lennie (subscriber, #49641)
The register mentions some more about the advantages and specifications:
Posted Feb 15, 2013 18:13 UTC (Fri) by nix (subscriber, #2304)
Posted Feb 20, 2013 0:49 UTC (Wed) by man_ls (subscriber, #15091)
Posted Feb 21, 2013 21:11 UTC (Thu) by mikewd (subscriber, #46016)
The problem is that the diffusion rate of helium through glass or epoxy and other glues and insulators can be quite high at room temperature (as a low temperature physicist well knows). So the container needs to be all metal with a soldered or welded seal.
Posted Feb 22, 2013 10:28 UTC (Fri) by khim (subscriber, #9252)
So the container needs to be all metal with a soldered or welded seal.
Well, we are talking HDDs here. They used "all metal" containers for decades now anyway. Usually they had some filters and were not welded shut, but that is minor change IMO.
Posted Feb 22, 2013 18:12 UTC (Fri) by magila (subscriber, #49627)
Making all of these openings impermeable to He is not a minor change and will likely significantly increase the cost of the drive.
Posted Feb 14, 2013 23:43 UTC (Thu) by dlang (✭ supporter ✭, #313)
Posted Feb 1, 2013 16:49 UTC (Fri) by felixfix (subscriber, #242)
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