Does NVMe Flash Mean the End of SAS Flash?

Before NVMe, most flash systems were either serial attached SCSI (SAS) or Serial Advanced Technology Attachment (SATA) based. In all-flash arrays, SAS was the preferred protocol because of its higher bandwidth and ability to support multi-port connections. NVMe is the logical upgrade to these technologies because of its higher command count, greater queue depth, and native PCIe connectivity; however, NVMe does not replace SAS. Today SAS flash drives are still less expensive than their NVMe alternatives, and most of the high capacity and ultra-high capacity flash drives are SAS based.

The Role of High Capacity Flash

Several vendors are committing to deliver 50TB+ high-density flash drives in 2019. A 24-drive flash array, using 50TB drives, delivers 1.2PB of raw capacity and potentially over 1PB after protection. Using high-capacity flash drives, organizations can achieve Petabytes of capacity in just a few rack units. These systems are ideal for active archive use cases where extreme performance isn’t required, but rapid access is.

The challenge for IT is how to leverage these high capacity flash drives without increasing the IT burden of having to manage separate systems. IT needs to not only look for vendors that can provide a choice of NVMe or SAS based flash arrays but also the ability to use the same storage software to manage those systems. Many vendors offer the option of SAS or NVMe flash systems, but few provide the option under a single management GUI.

Hybrid Flash

When flash first came to the data center, the most common method was in a hybrid array, which mixed SAS based flash with hard disk drives to help offset the cost of the premium-priced flash technology. The continual decline in flash pricing combined with data efficiency technologies like deduplication and compression is creating price parity between flash and hard disk systems. Price parity between the two technologies reduces the value of hybrid arrays for many vendors. Vendors with the intelligence in their software to automatically tier between two different types of storage though, can leverage that technology to mix SAS and NVMe drives thus creating a new type of hybrid flash array. The flash system can leverage the NVMe tier for high-performance workloads and the high-capacity SAS-based flash tier for other workloads or dormant data.

The tiering between SAS and NVMe flash tiers requires further development though since the software can no longer base data placement decisions solely on access patterns. The storage software now needs to understand “data intensity” to make sure accessed data can take advantage of the higher performing NVMe tier.

Object Flash

Another option is for the organization to leverage the high-capacity flash drives in object storage systems to create an active archive. Most object storage systems already support flash drives, but most can’t move data automatically between a primary storage system and an object storage system. Third party solutions exist to perform the analysis and movement of data between the two storage systems, but vendors that provide both technologies should have an advantage in providing a deeper more seamless integration between the tiers.


In this blog series we’ve busted several of the myths surrounding NVMe. While NVMe offers unprecedented performance to organizations of all sizes, each organization needs to evaluate its needs carefully. In most cases, leveraging a flash system that leverages NVMe flash while still taking advantage of traditional connectivity instead of replacing or upgrading the existing network is the best fit for the organization. At the same time, they should make sure that the features, like snapshots and replication, are still available to them when they move to an NVMe array. Finally, organizations should not rule out SAS or even Hybrid based storage systems to balance performance requirements against costs.

Join us live on January 30th at 1:00 pm ET / 10:00 am PT to get the answers to these and other NVMe questions. Plus ask your own, during our Q&A session with the experts. All pre-registrants will receive a free copy of Storage Switzerland’s latest eBook “Busting the NVMe Flash Myths,” in advance of the webinar.

George Crump is the Chief Marketing Officer at VergeIO, the leader in Ultraconverged Infrastructure. Prior to VergeIO he was Chief Product Strategist at StorONE. Before assuming roles with innovative technology vendors, George spent almost 14 years as the founder and lead analyst at Storage Switzerland. In his spare time, he continues to write blogs on Storage Switzerland to educate IT professionals on all aspects of data center storage. He is the primary contributor to Storage Switzerland and is a heavily sought-after public speaker. With over 30 years of experience designing storage solutions for data centers across the US, he has seen the birth of such technologies as RAID, NAS, SAN, Virtualization, Cloud, and Enterprise Flash. Before founding Storage Switzerland, he was CTO at one of the nation's largest storage integrators, where he was in charge of technology testing, integration, and product selection.

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