In a news story out of Singapore Institute of Materials Research and Engineering (IMRE), Dr. Joel Yang has demonstrated 6X the current density on disk platter media, or up to 3.3 Terabits /square inch (Tb/sqin). And it all happens due to salt (sodium chloride) crystals.
I have previously discussed some of the problems encountered by the disk industry going to the next technology transition trying to continue current density trends. At the time, the then best solution was to use bit-patterned media (BPM) and shingled writes discussed in my Sequential Only Disk!? and Disk trends, revisited posts. However, this may have been premature.
Just add salt
It turns out that by adding salt to the lithographic process used to disperse magnetic particles onto disk platters for BPM, the particles are more regularly spaced. In contrast, todays process used in current disk media manufacturing, causes the particles to be randomly spaced.
More regular magnetic particle spacing on media provides two immediate benefits for disk density:
- More particles can be packed in the same area. With increased magnetic particles located in a square inch of media, more data can be recorded.
- Bigger particles can be used for recording data. With larger grains, data can be recorded using a single structure rather than using multiple, smaller particles, increasing density yet again.
Combining these two attributes increases disk platter capacities by a factor of 6 without having to alter read-write head technology. The IMRE team demonstrated 1.9Tb/sqin recording capacity but fabricated media with particles at levels that could provide 3.3Tb/sqin. Currently, the disk industry is demonstrating 0.5Tb/sqin.
Other changes needed
I suppose other changes will also be needed to accommodate the increased capacity, not the least of which is speeding up the read-write channels to support 6X more bits being accessed per revolution. Probably other items need to be changed as well, but these all come with increased disk density.
Before this technique came along the next density levels was turning out to be a significant issue. But now that salt is in use, we can all rest easy knowing that disk capacity trends can continue to increase with todays recording head technology.
Using the recent 4TB 7200RPM hard drives (see my Disk capacity growing out-of-sight post), but moving to salt and BPM, the industry could potentially create a 24TB 7200RPM drive or for the high performance 600GB 15KRPM drives, 3.6TB high performance disks! Gosh, not to long ago 24TB of storage was a good size storage system for SMB shops, with this technology, it’s just a single disk drive.
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