HGST (Formerly Hitachi’s hard drive division) has been talking about its helium storage devices for several years and the firm is finally ready to ship the new drives for enterprise deployments. The Ultrastar Archive Ha¹⁰ isn’t just filled with helium — it also uses new Shingled Magnetic Recording (SMR) to write data to the disk. While this allows for unprecedented areal density, there are some caveats that make the drive ill-suited to conventional consumer applications. It’s an offshoot of the earlier-launched He⁶, which uses helium, but not SMR.
First, a word on SMR itself. SMR is the latest advance in recording technnology designed to ensure that consumers and businesses have enough storage space for… erm, office documents. It’s my personal opinion that hard drive manufacturers don’t get nearly enough credit for the work they’ve done to expand storage capacities. Imagine if Ford rolled out a new 2016 Escort capable of holding the population of China in a smaller footprint than its 1981 model year, and you’ve got some idea of just how drastically hard drives have advanced in the intervening decades.

Unfortunately, all good things come to an end, and conventional HDD scaling (even assisted by perpendicular recording) is hitting a wall. Areal density becomes difficult to scale using conventional methods because it’s no longer possible to focus a sufficiently powerful magnetic field on a single bit of the drive. Shingled magnetic recording boosts drive density not by scaling the areal density to ever-higher levels, but by laying tracks across each other, in shingled fashion.

The advantage of laying the tracks down in this fashion is that you pack data more closely together. The disadvantage is that rewriting tracks will damage the data on subsequent tracks. The only way to prevent this is to read the entire data block, modify the necessary section, and then re-write the rest of the track. This can lead to huge write amplification — if a 4KB update needs to be performed to a 64MB area of track, then the entire 64MB has to be read into RAM and laid back down with the modified 4K section. To reduce the impact of this write amplification, the drives are divided into bands — contiguous blocks of data that are treated as a unit.
It’s important to avoid random reads and writes as much as possible when using SMR, however, which is why HGST is marketing these drives as “cool” to “cold” storage — meaning data that’s written very few times and accessed only on occasion. If the drive is being regularly written and re-written, the performance penalties will quickly become severe. The HGST drives also require extensive modification and drive software in order to operate properly.

Hitachi has an open-source project, libzbc, that can be integrated into Linux to implement support for its now Ha¹⁰ drives. Absent such support, the drives can’t function — these aren’t your typical plug-and-play hard drives.
Right now, it’s hard to see where SMR drives will fit into future consumer products. Tech Report, erm, reports that the rated performance on the new hardware is just 157MB/s sequential read and 68MB/s sequential write. Meanwhile, adding the helium capabilities to drive up storage densities will add its own significant costs. All drive technologies require a launch period before they start to hit attractive prices, but pushing the envelope on HDD storage through noble gases and particular recording methods with some noted drawbacks seems an ill fit for the larger consumer market. It’s worth noting that SMR isn’t the only game in town for pushing the envelope on hard drive capacity — another technology, Heat Assisted Magnetic Recording, or HAMR, is currently expected to reach market by 2016 or 2017.