Western Digital keeps HDDs relevant with major capacity boost

It’s hard to advance a technology that could be facing obsolescence, but that’s what Western Digital and its chief rival Seagate Technologies are doing. Hard disk drives (HDD) have lost the low-end capacity market to solid-state drives, and SSDs are slowly but surely making their way to higher capacity dominance.

So, the makers of HDDs have stuck to the one place where they still have an advantage, and that is capacity. For an SSD to increase capacity by 50%, it needs 50% more chips, and that means a 50% increase in price. But hard drives, thanks to some technical wizardry, continue to see an increase in capacity and can now put 40% to 50% more data on a single platter than previous versions allowed.

Western Digital unveiled the second generation of its Ultrastar DC HC680 drive family of drives in 24TB and 28TB capacity using shingled magnetic recording (SMR) technology, which is designed specifically for data centers. It also introduced new enterprise drives, the WD Gold Enterprise and Ultrastar DC HC580 24TB, with conventional magnetic recording (CMR).

This matches Seagate’s high-end X24 drive, which tops out at 28TB and also uses SMR technology.

SMR technology – along with the heat-assisted magnetic recording (HAMR) technology created by Seagate – represents a new method of increasing storage density.

The primary difference from older technology is how the bits are arranged and packed onto the disk platters. Through advanced electrical engineering, areal density (data stored per square inch on a platter’s surface) can be increased by up to 40% within the same space as traditional hard drives.

There are also physical changes. SMR and HAMR drives can pack up to 10 platters in a standard 3.5” hard disk enclosure. There is no room for error with this level of packaging, and no room for heat. To reduce heat friction, the drives are filled with helium, which makes them cooler and less prone to overheating.

Because heat is such an issue, SMR and HAMR drives have a lower power draw than standard disks, so even though capacity is greater and there are more platters in the drive, SMR and HAMR drives consume less power per gigabyte.

They come with caveats, however. With so much technology packed into such a tight space, there’s greater opportunity for failure. While Western Digital and Seagate have undoubtedly tested the drives rigorously in their labs, it’s not until we have real world use cases that were going to know if the lifespan of these drives is comparable to a standard disk or not. No doubt BackBlaze will be on top of this issue with its quarterly hard drive failure reports.

Another negative for the new drive technology is a slower write performance. That’s a logical tradeoff given that the drives are packing more data per platter than the old technology. A performance hit is inevitable. The performance hit varies based on how full a drive is, because a drive has to essentially defragment itself every time it writes data. Fortunately, in their most common use cases – archival, mass storage, cold storage – write performance is less of a concern than read performance.

IT departments are gaining even more dense options with these new high-capacity drives, but there is cost in write performance, said Brent Ellis, storage analyst for Forrester Research. “So, this is really meant to address archive and low- to mid-tier storage needs. Higher performance storage will be on SSD and NVMe,” Ellis told me.

HDDs will long have a role in large, cloud-scale storage environments, but SSDs are catching up, he added.

“Innovations like QLC have made capacity flash arrays a possibility, giving enterprises access to reasonably dense storage with an order of magnitude better performance and significantly less power draw. I think when you add in all the factors, capacity flash starts to look very attractive and promises to close the gap even further. HDDs still win in the terabytes per dollars category, but I think that time is limited, especially when you add in heat, mechanical failure, and power draw,” Ellis said.