Seagate Announces It’s Successfully Built 16TB HAMR Drives
Seagate has announced the successful completion of a 16TB HDD built using HAMR (Heat Assisted Magnetic Recording) in its own internal labs. The company has announced that its new HAMR drives work as expected in various scenarios, and that database and enterprise customers will need to make no changes when they hook the drives up. That’s a significant point compared with some other drive technologies we’ve seen in this space.
Prior to the development of HAMR, higher drive capacities have been enabled by the adoption of shingled magnetic recording, using helium to pack more platters into the same drive enclosure, or both. Shingled magnetic recording suffers a write penalty compared with conventional HDDs because the “shingle” in question overlaps drive tracks. Writing to a track therefore overwrites adjacent tracks and requires them to be rewritten as well. Before this, we saw a transition point between HDDs with 512 bytes per sector and 4K per sector, which also required special software (on older operating systems) to make the drives perform properly. The idea that a major change in HDD technology might require an OS update or special software support, in other words, isn’t crazy — but Seagate says it’s not a problem here.
HAMR avoids the performance loss associated with shingled magnetic recording by heating the drive before writing to it. Temporarily increasing the temperature at the spot being written makes it easier to establish the necessary magnetic field and to write to a smaller region, allowing for an effective increase in areal density. This is no small technical feat. I don’t normally quote Wikipedia in an article, but this summation of the technical difficulty is accurate.
The regions being written must be heated in a tiny area — small enough that diffraction prevents the use of normal laser focused heating — and requires a heating, writing and cooling cycle of less than 1 nanosecond, while also controlling the effects of repeated spot-heating on the drive platters, the drive-to-head contact, and the adjacent magnetic data which must not be affected. These challenges required the development of nano-scale surface plasmons (surface guided laser) instead of direct laser-based heating, new types of glass platters and heat-control coatings that tolerate rapid spot-heating without affecting the contact with the recording head or nearby data, new methods to mount the heating laser onto the drive head, and a wide range of other technical, development and control issues that needed to be overcome.
Paragraphs like this are part of why I still have a lot of respect for spinning media, despite the fact that its overall performance these days doesn’t hold a candle to SSDs. Hard drives may not be fast, but the technical work that’s gone into increasing their capacities is cutting-edge and impressive in its own right. The difficulty of storing more data in the same size form factor has increased, just as the difficulty of scaling silicon to new nodes has increased as well. Much of the company’s blog post emphasizes that the HDD has been through an entire battery of tests and confirmed to run perfectly normally in every regard — an emphasis intended to highlight that despite the amount of new technology Seagate has developed, the drop-in experience will be standard.
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