Magnetic recording breakthrough reported • Hacker News Board

Re: Magnetic recording breakthrough reported

#31

Post by delinka » Wed, Feb 08, 2012, 2:10 PM UTC

tocomment wrote: post #30

I'm confused. Doesn't a writable DVD work on the same principle of using a laser to heat small portions of a spinning disc? Why should this methods be so many orders of magnitude faster than writing to a DVD?

First, keep in mind that this is a modification to hard drives and not DVD-like equipment. The heat pulses in the case of the article are still modifying the magnetic bits on a spinning metal disk.

Second, it seems that it's faster to generate these heat pulses than it is to switch the magnetic orientation of the write head. I haven't looked into the physics, but this is the only plausible explanation my limited imagination can fathom.

Re: Magnetic recording breakthrough reported

#32

Post by gfodor » Wed, Feb 08, 2012, 2:54 PM UTC

Since this doesn't affect read speed, it's interesting to imagine what would happen if there were a de-facto asymmetry between read and write speed for hard disks. I'd guess you might end up in a world where a "disk" actually becomes a "RAID-array-in-a-box" so parallel reads could make the read speed be close to the write speed.

Re: Magnetic recording breakthrough reported

#33

Post by Lagged2Death » Wed, Feb 08, 2012, 4:24 PM UTC

If the heat pulses only toggle the state of the nano-islands, then it makes little practical sense to speak of 'write speed,' since you'll have to determine the current state of the bits (that is, you'll have to read them) before you attempt to write them.

Re: Magnetic recording breakthrough reported

#34

Post by InclinedPlane » Wed, Feb 08, 2012, 5:47 PM UTC

ars wrote: post #19

InclinedPlane wrote: post #14

Earlier quoted context omitted.

Sort of a moot point regardless. If you have a spinning disk the average latency and maximum read or write speed is determined by the speed of the disk.

Not necessarily. For example you could have many read heads and read from the disk much faster by reading in parallel. It's complicated to do, but it is possible. You can also increase the areal density, which means more bits fly past the head per second, which also increases speed, even though you can't increase the rotational or seek speed.

Increasing the number of platters improves read/write throughput independent of the low-level technology used. As far as increasing density, that only scales relative to the square root of areal density. If you increase density by a factor of 100 you only increase the number of bits per track by a factor of 10.

The same rules don't apply to mram, of course, but from the article I'm not entirely sure if these techniques are useful for such designs.

Re: Magnetic recording breakthrough reported

#35

Post by redthrowaway » Thu, Feb 09, 2012, 1:21 AM UTC

replax wrote: post #25

redthrowaway wrote: post #18

Earlier quoted context omitted.

On top of the read problem, they have to deal with the fact that HDDs are just really energy-inefficient. With the world going to mobile, we can't predicate the future on the need for moving parts. It's a damned cool technology, and I hope it leads to something useful, but I just can't see it becoming the prevalent paradigm.

Yes, you're right the world is going mobile and in mobile less (no) moving parts is better (more durable etc.) That is also why I think that consumer grade devices will be unlikely (unless read speeds are bumped up, too) But mobile, in our case, means also a shift to the cloud, where significant more potent storage technologies could make a real difference. I really hope, too, that technology will lead to something n…

Fair enough. It's hard to see where these kinds of write (but normal read) speeds would be necessary, even in a server farm, but I guess the beauty of enabling technologies is that they allow for use cases no one could have imagined when they were conceived.