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HAMR Hard Disk Drives Postponed To 2018 (anandtech.com)
An anonymous reader writes: Unfortunately the hard disk drive industry is not ready to go live with Heat-assisted Magnetic Recording (HAMR). The technology is yet not reliable enough for mass production. Over the years, producers of hard drives, platters and recording heads have revealed various possible timeframes for commercial availability of drives with HAMR technology. Their predictions were not accurate. The current goalpost is set to year 2018. While solid state disks based on Flash memory keep seeing rapid improvements as well, HDDs still kick butt in scenarios where high areal density is more important than ripping transfer speeds. The areal density of HAMR products is predicted to exceed 1.5 Tb per square inch.
Oh wait ... not yet
The summary lists HDDs as viable vs SSDs when "high areal density is more important than ripping transfer speeds" but in most applications it's the random access time that's more useful and SSDs are better than HDDs in this regard by several orders of magnitude.
Of course it's not reliable, who the hell thought that using a HAMR on hard drives was a good thing? That's what I use to destroy hard drives!
Dear Dice Editors:
If you are going to post a summary which says what *might* be possible in the future, it's helpful to know what the current state-of-the-art is. For example, if you are going to have a summary that says the areal density of HAMR products is predicted to exceed 1.5 Tb per square inch it would be nice to know that Seagate is already shipping a drive with 1.34Tb/in^2 according to Wikipedia.
As it turns out, context matters when giving statistics, or there is no reference to know if the statistic means anything. Given what I found in 30 seconds of using Google, that would mean that HAMR is expected to yield ~12% increase in density from the current state-of-the-art.
You're welcome.
Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
Areal density doesn't mean shit. Volumetric density is what counts.
As another commenter pointed out, the 1.5Tbit/in^2 number in the posting (which is taken from the original article) is pretty bogus. Seagate's 2TB 7mm 2.5" drive has an areal density of 1.32Tbit/in^2, and it's probably a safe bet that they (and WD) can wring another 15% density improvement out of SMR technology in the next year or two.
For those commenters bemoaning the fact that the highest density drives today are SMR rather than "regular" drives, get over it - the odds of conventional non-HAMR, non-shingled drives getting much denser than the roughly 1TByte per 3.5" platter we see today are slim to none:
To get smaller bits, you need a smaller write head. That smaller write head has a weaker magnetic field. The weaker field means the media has to be more easily magnetizable (i.e. has lower coercivity). The lower coercivity media needs to have a bigger grain size (size of the individual magnetic domains), so that grains don't flip polarity too often due to thermal noise.
Since a bit can't be smaller than a grain, that means that smaller your write head is, the larger your minimum bit size is. Eventually those two lines cross on the graph, and it's game over.
Two ways of getting out of this are SMR (shingled magnetic recording) and HAMR (heat-assisted magnetic recording):
SMR - stop making the write head smaller, but keep making the bits smaller. Overlap tracks like clapboards on the side of the house (where'd this "shingle" nonsense come from?), allowing small bits with large write heads. Of course this means that you can't re-write anything without wiping out adjacent tracks, which means you need something like a flash translation layer inside the drive, and because of that, random writes might be *really* slow sometimes. (I've seem peak delays of 4 seconds when we're really trying to make them behave badly)
HAMR - Write your bits on low-coercivity media with a tiny, wimpy head, and store them on high-coercivity media with tiny magnetic grains. How do you do this? By heating heating a high-coercivity media with a laser (say to 450C or so) to reduce its coercivity to reasonable levels, then letting it cool down afterwards. But you need a big laser (20mw?) on each head, which causes a whole bunch of problems. Which is probably why they're delaying them.
Oh, and you can overlap tracks on HAMR drives, creating an SMR HAMR drive, with even higher density but the performance problems of both technologies. Which they'll probably do as soon as HAMR hits the market, because with today's SSDs the market for fast HDDs is dying a very quick death.
3½" diskettes were never referred to as a hard disk, like their 5 1/4 counterparts they were referred to as floppies. Named after the internal magnetic medium, not the casing.