Last Gasp For Hard Disk Drives

A new, a pint-sized, 15,000 RPM hard disk drive has just been released to the market. It's a fast little product from Western Digital's HGST that is a capacity match for traditional enterprise 3.5-inch drives. Fitted into only a 2.5-inch form factor, however, the Ultrastar C15K600 boasts more than double the performance of existing drives.

The product doesn't come with a Fibre Channel interface, so it isn't a complete throwback to the good old days. But it ships without onboard flash or any of the other new industry tricks, such as helium filling.

The question is, "Who needs it?" That's not pejorative, but this drive goes against the current wisdom of the disk drive business. It's generally accepted that superfast SSD or flash arrays will overtake the market for enterprise performance storage -- a process that's already happening.

In a press release announcing the new Ultrastar, HGST cited guidance from IDC indicating that the demand for 15K drives in 2016 would be twice that for SSDs. in 2016. In addition, HGST said:

First, our customers continue to use 15K HDDs along with a complement of SSDs in tiered pools of storage, depending on their performance, capacity, and power efficiency requirements. Our new Ultrastar C15K600 fills a need for storage that is more cost effective than SSDs, and has the performance, reliability and capacity requirements needed by mission-critical enterprise applications. Also, we see that the industry is transitioning away from 15K 3.5-inch hard drives to smaller 2.5-inch drives to help reduce space requirements, while offering comparable capacities to the legacy 3.5-inch 15K products.

This seems to suggest that legacy arrays are driving the need for the new product, but 2.5-inch drives generally don't fit arrays and need physical adapters. The last sentence suggests new 2.5-inch arrays could be a major factor in the opportunity.

Looking a bit deeper, the legacy story has a few holes. Arrays tend to be homogenous in drive types, and enterprise drives have had long lifecycles as a result. Certainly, the ability to get doubled performance might be an argument for upgrading all the drives in an array, but given the alternatives of SSD and all-flash arrays, it isn't very strong.

The tiering comment is also a bit off-key. Creating a current-view tiering involves a solid-state front-end with bulk spinning drives behind it. Flash/SSD products provide the IOPS, while the HDDs provide the terabytes for archiving, backup, and low-usage data. There doesn't appear to be a use case for SSDs and fast (but expensive) enterprise 15K HDDs, since any such case is better resolved with more SSDs.

Drives like this could give life to new large capacity arrays with, say, 60 drives in a 3U cabinet. A 36-terabyte box like this would deliver just 18,000 IOPS, which is far below the slowest single SSD on the market. We must remember that we have been conditioned by 30 years of performance stagnation in HDDs to think only of capacity when it comes to choosing drives. 

So how much does the capacity really cost? Terabyte consumer grade multi-level cell SSDs retail for around $600. De-provisioning them to 600 GB provides an excellent wear life. While HGST hasn't publicly announced a price for the new Ultrastar drive, based on similar enterprise drives it won't be much cheaper than $600. Of course, the OEM vendors may choose to set premium prices on SSDs for their arrays, and having the new HDD as an option allows for more pricing games. That seems a bit like a bait and switch, with SSD coming out the winner. 

In sum, the use cases for this type of drive aren't obviously strong. It will likely find a market in Japan, for example, where conservatism is king, but SSD is running a better race elsewhere.

The new drive is nice example of design in its class, and a tribute to its design team. Market success would be well deserved, but the deck may be stacked against it. Don't be surprised if we look back in a year or two and say, "This was the best -- and the last -- enterprise HDD."

State Of Enterprise Storage Solid state alone can't solve your volume and performance problem. Think scale-out, virtualization, and cloud. Find out more about the 2014 State of Enterprise Storage Survey results in the new issue of InformationWeek Tech Digest.