No SSD-HDD Price Parity Before 2020

Editor's note: A recent blog post about SSD pricing by Jim O'Reilly certainly stirred up a lot of debate. The post has received more than two dozen comments, including two comprehensive responses from Howard Marks, founder and chief scientist at DeepStorage, and Network Computing contributor. We thought it worthwhile to highlight his comments here. This is an edited compilation of his comprehensive response to the blog.

While it's possible that for desktop applications SSDs will reach price parity with HDDs in 18 months as you predict, that will not be true for data center applications for several years.  While I think that many users, including corporate users and the cloud savvy, would be better served by using smaller SSDs and external storage than large SSDs, today that's not primarily a cost-based recommendation.

You seemed very impressed that a 1 TB SSD was available for just $350. On Newegg today, that would be a SanDisk X300 client device, and a competitive 1 TB HDD from WD or Seagate would cost about $50.  While the SSD could be about half what an equivalent SSD would have cost last year, the HDD is 1/7th the cost of the SSD. 

If we look at data center use cases, the price differential is even greater. An Intel DC S3500 1.2 TB SSD costs $1,110 (I'm willing to call it $1/GB) where a 6TB Seagate Archive drive is $240 or $0.04/GB -- a difference of 25 times. Even if I use the SanDisk X300 as my cost model, the price difference is almost 10:1.

By the way, those SSDs that NetApp said they never saw fail they weren't SanDisk X300s or even Intel DC S3500 (the low end of Intel's enterprise line), but more like the Intel DC S3700 with better flash and more overprovisioning. The DC S3700 is $1,200 for 800 GB or 1.5 times more expensive than the DC S3500 on a per GB basis.

In the desktop market we'll reach parity because desktop users need only say 500 GB, and the cost of small disk drives stops falling once the desired capacity can be met with one platter. A 500 GB disk costs $40 vs the $50 of a 1 TB disk for just this reason. The minimum price of a disk has to cover a platter, head and spindle motor so small disks are more expensive per GB than large.  When the 512 GB SSD hits say $100, intelligent users will abandon the HDD.

However, in the data center we buy both flash for performance and spinning disks for capacity, therefore we buy big disks that cost a lot less per GB, especially when you figure in the cost of an array or server drive slot.

For the cost of SSD and HDD to cross at say 4TB as you predict, SSD costs would have to come down 80%, a factor of five, in 18 months and hard drive technologies like bit-patterned media and HAMR would have to fail so that hard disk prices didn't decline.  

If we assume that SSD prices fall at 40%/yr (a bit faster than historical rates) and HDDs decrease at 15% (A bit slower than historical rates), it's still five years before parity.

O'Reilly's point-by-point response drew a point-by-point comment from Marks. You can read their exchange here.