Faster Flash with NVMe Over Fabrics

Broadcom Briefing Note

No matter how fast the storage infrastructure is, IT professionals can count on users and application owners to want more. Flash storage goes a long way toward appeasing the appetite for performance. But it is the constant in the performance equation and outperforms the surrounding eco-system that delivers data to the users. For the first time the storage media (flash), out performs its surrounding components. Each component introduces latency. Fixing latency is key to making flash faster.

Step 1: NVMe

The first step in improving flash performance is the introduction of NVMe which is a storage protocol interface that is designed specifically for flash media. Prior to NVMe, flash was either retrofitted to with SCSI or the vendor provided proprietary drivers to by-pass the SCSI protocol stack. Delivering SCSI improved compatibility at the expense of performance, proprietary drivers improved performance at the expense of compatibility. NVMe resolves the paradox by creating an industry standard access method supported by a wide variety of storage manufacturers.

Step 2: NVMe over Fabrics

Fixing the way an application or operating system interfaces with the flash media is the first step. The problem is NVMe, when first introduced, was primarily designed for PCIe based flash devices installed in the server and then later solid state disk (SSD). The problem is the clustering of many applications and operating environments and as a result require shared storage. Additionally, enterprises consider shared storage as the most efficient way to provision storage resources. In fact, more than 90 percent of All-Flash Arrays (AFA) attach through a fibre channel network.

Shared storage systems and networks all continue to use traditional IP and Fiber Channel protocols which essentially leverage a SCSI transport. The problem is flash exposes not only the latency of the storage network but also latency as the result of the continued use of SCSI. NVMe over fabrics allows these various networks to communicate via NVMe instead of SCSI, reducing latency significantly.

Emulex NVMe over Fiber Channel

When IT professionals hear the word “new” they also assume “rip and replace”. Emulex, a division of Broadcom, is enabling a crawl, walk, run approach to NVMe transition. Emulex’s current Gen 6 fibre channel cards will support NVMe, all that is required is a driver update. Additionally NVMe and legacy SCSI are supported simultaneously so that SCSI SAS/SATA HDDs co-exist with NVMe Flash SSDs.

The dual mode approach is ideal and practical for the today’s data center which has very little, if any, NVMe flash storage. Now organizations can implement NVMe flash for specific use cases where the reduction in latency, which Emulex claims to be around 50 percent, will pay off. Then the organization can continue to use SCSI-based flash and even hard disk drives for data that is less sensitive to latency.

StorageSwiss Take

Because of the latency issues flash exposes in the infrastructure, data centers are careening dangerously to complex direct attached storage infrastructures. NVMe of fibre channel addresses the concern by reducing fabric latency by 50 percent potentially eliminating the need for local storage in all but the most extreme use cases. The fact that a data center can move to NVMe gradually as the need arises, while supporting legacy protocols, is the icing on the cake.

Twelve years ago George Crump founded Storage Switzerland with one simple goal; to educate IT professionals about all aspects of data center storage. He is the primary contributor to Storage Switzerland and is a heavily sought after public speaker. With over 25 years of experience designing storage solutions for data centers across the US, he has seen the birth of such technologies as RAID, NAS and SAN, Virtualization, Cloud and Enterprise Flash. Prior to 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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Posted in Briefing Note

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