R&D: TDK Uses Lasers To Double Hard Disc Capacity, Helping Save HDs From Extinction

Here’s a development that will bring joy to those that prefer to hear mechanical noises from their hard discs instead of the inky silence of the new solid state drives. The current perpendicular magnetic recording technology used in today’s hard discs are due to hit a brick wall within a couple of generations or so. This will finally give SSDs the chance to make mechanical drives obsolete once and for all when their capacities increase and the prices drop. To get around this, TDK intend to use lasers coupled with a high coercivity material to achieve this capacity improvement. The coercivity value of a material is a measure of how difficult it is to magnetize ie how strong the magnetizing field needs to be. A material with low coercivity, is easy to magnetize, but it can also lose its magnetic imprint (north and south domains) easily, especially with densely packed data and is easy to erase with stray magnetic fields and to some extent, physical shock. Conversely a material with a high coercivity value can be damned hard to magnetize, but will keep its magnetic imprint much more stably and crucially for data storage, can retain much smaller magnetic domains, giving rise to greatly increased storage capacity for all that ever increasing avalanche of crucial data, such as music files, dodgy videos and humungous video game installs.

The coercivity value of a material reduces dramatically with heat, especially a lot of it, which can completely demagnetize the material as the atoms vibrate strongly with thermal energy. Therefore, the trick with writing data to high coercivity materials is to heat them first, write the data and then cool them quickly before it’s lost. This is called Heat Assisted Magnetic Recording (HAMR) and is where TDK’s new laser technology comes in, as it can do this for tiny magnetic domains and using great precision. The catch at the moment, is finding such a suitable high coercivity material to work with the new laser technology, but development is ongoing.

As this technology isn’t ready for prime time, TDK is keeping quiet about the precise details of how it works. Developing new storage technology is very expensive for any one company, therefore hard drive manufacturers club together and belong to the Storage Technology Alliance to pool their resources together. However, when the new technology is ready, we could be looking at the upcoming 4TB drives using 4 platters now, have 8TB capacity, or conversely, the same capacity with half the platters. This explains why almost as soon as one drive manufacturer brings out a new high capacity drive, the others follow in short order, all using the same technology and hopefully without too many patent disputes.

To add a further twist to this story, it looks like HAMR alone won’t be enough to double capacity, so it looks like bit-patterned media (BPM) will be used with it, too. BPM means literally what it says, a predefined physical pattern is etched onto the recording media to assist with recording and retaining data.

So hurrah for mechanical hard drive aficionados, mechanical hard drives are not going to succumb to solid state drives any time soon. Of course, the development that we all want to see, are SSDs with the capacity of hard drives, that don’t have the limited write cycles of current flash memory and don’t write in blocks, but require a page erase cycle which slows them down and complicates things. However, this tech is unfortunately, not even on the horizon. When it does finally arrive, perhaps an artificial mechanical rattle could be added to these for those seeking that nostalgic feel for their PCs?

Source: The Register