What’s Up With 15K RPM Hard Disks?

By Philip Trautman, NetApp


NetApp has been getting a lot of questions about 15K RPM disk drives lately. As you may have heard, 3.5” LFF 15K RPM HDDs are being phased out by disk manufacturers. At the same time, 2.5” SFF 15K RPM disk drives face an uncertain future, and remain expensive.


Because of this, 2.5” 10K RPM disk drives have become a better option. These disks deliver twice the density in the same rack space, and they can be combined with SSDs in a Flash Pool aggregate that delivers great performance and capacity. Flash Pool  provides more performance at a lower cost per GB, so you come out ahead.



The HDD Market Is in Transition


As you can see in the following figure, total industry 3.5” 15K RPM drive shipments are already in decline and will cease entirely in 2015. Total shipments of 2.5” SFF 10K RPM disk drives already far exceed 3.5” drive shipments.





2.5” SFF 15K RPM disk drives have not taken off to the same degree, and are not predicted to become a significant market force during the forecast period for a number of reasons:

  • 15K RPM disk drives are harder to produce, making them more expensive.
  • 15K RPM disk drives aren’t available at the capacity points of their 10K RPM cousins. NetApp is already shipping 1.2TB 2.5” 10K RPM disks. The largest 2.5” 15K RPM disk drive is 600GB. That’s a 2X capacity advantage, and it’s expected to widen further.
  • While 15K RPM drives offer roughly 50% more IOPS (as you would expect) the cost per GB per IOPS is also 50% higher.
  • SSD or a combination of SSD (or Flash Cache) and HDD offers far superior performance density and lower latency.




Performance Options

So, if you’re in the market for performance disks, what options should you be considering? We compared 2.5” 10K RPM, 2.5” 15K RPM, 3.5” 15K RPM, Flash Pool (SSD plus 2.5” 10K RPM) and pure SSD configurations in the lab to come up with the best set of recommendations.

  • Performance Disks Alone. If you’re in the market for a solution based solely on performance disks, then 2.5” 10K RPM disks are your best option. They have the lowest cost in terms of dollars per GB—2.5” 15K RPM drives are 160% more expensive on a capacity basis. NetApp offers a complete portfolio—600GB, 900GB, 1.2TB—so you can optimize the number of spindles to achieve the right capacity and performance for a wide range of requirements.
  • Hybrid Configurations. If you need greater performance, choose a hybrid storage configuration using a Flash Pool aggregate that combines HDDs and SSDs. NetApp offers a broad portfolio of SSDs—200GB, 400GB, 800GB, and1.6TB—so you can create an optimal configuration. NetApp tools help you determine how much cache you need for your workload. An equivalent configuration delivers 3X the IOPS of 2.5” 15K drives, at 31% LOWER COST.
  • Maximum Performance. If you need maximum performance with minimum latency from every I/O operation, consider a FAS system with all-SSD aggregates or the NetApp EF550 Flash Array.



Storage Economics Favor Hybrid Configurations

Currently, the economics of storage really make hybrid configurations the sweet spot. Hybrid storage offers a low cost per GB relative to 2.5” 15K HDDs, with great performance. To find out more about all your media options, go to the NetApp Disk Shelves and Storage Media page. You can also join or start a conversation on the NetApp Storage System Community page or contact NetApp Sales.


It would be interesting to see  3.5" LFF 7K drives (with and without SSD) on this table for comparison.

Also Hybrid 7K/SSD drives.