SAS is Dead; Long Live SAS!

By Mike Tomky - 2015-08-06

With all of the attention around PCIe-based storage offerings, it is not difficult to understand why some believe that Serial Attached SCSI (SAS) as a storage interface has run its course. After all, do we really need three different storage interfaces for SSDs?

The answer is YES!

While PCIe for storage is certainly exciting with the ability to move data closer to the CPU and complete processing tasks in record time, the protocol was not designed with the deep error-handling capabilities of SAS. In fact, NVMe (the leading protocol running on top of PCIe) was designed to be lightweight to create the least amount of latency possible. PCIe/NVMe is also new and lacks the decades of enterprise hardening and a robust ecosystem focused on the data-availability that SAS has accumulated. PCIe is ideal as an I/O accelerator and cache device. But, few CIOs are willing to trust their business-critical data on PCIe today.

In this world where we seemingly save every bit we create with the idea that we may need it again soon,  SATA continues to deliver on the promise of lower-cost solutions that are “good enough” for bulk data storage that needs to be accessed frequently but is not business critical. The boom of so called scale-out storage is thriving on the rapid increases in SATA capacities and the resulting decline in cost per gigabyte. While SSDs may never completely displace hard drives for cold storage, SATA meets the needs of this middle ground where large pools of data may need to be accessed frequently and the overlying software takes care of data availability.

So, what does that leave for good, old, reliable SAS? You should trust SAS with your very most important data. You know, the stuff that, if lost, could put you out of business.

SAS is the workhorse of the enterprise data center where business-critical information can NEVER be lost or corrupted. Big-iron storage systems may no longer be the darlings of the data center they once were but good luck trying to convince your IT managers to convert to anything else for the data that really matters, assuming they want to keep their jobs. An illustration of the continued importance of SAS can be found in industry research showing that the interface continues to hold a significant share of shipped drives. The difference today is that an increasing number of those SAS drives are SSDs instead of so-called performance HDDs (an oxymoron, for sure). Shipments of SAS SSDs are growing at an incredible pace as capacities reach the multiple terabyte range and prices approach a point where the cost/performance equation is compelling. Storage architects no longer have to make a choice between capacity and performance HDDs; SAS SSDs provide both capacity and performance and are a drop-in replacement for the old HDD.

This is why Micron’s announcement this week of the Micron® SAS 600 Series SSDs is so important. We believe in the importance of SAS as a critical component of business-critical storage solutions for many years to come and continue to invest in this important piece of our broad product portfolio. 

Each of the interfaces will continue to have a place in the enterprise for a long time to come. Use PCIe for IO acceleration, SATA for bulk data, and SAS as the workhorse of business-critical applications.

Courteous comments are welcome. You can find me on Twitter @mtomky.

You can also follow our main storage handle @MicronStorage to get insights and news related to the data storage industry.

Mike Tomky