NVMe overview primer

Updated 2/2/2018

This is the first in a five-part mini-series providing a primer and overview of NVMe. View companion posts and more material at www.thenvmeplace.com.

What is NVM Express (NVMe)

Non-Volatile Memory (NVM) includes persistent memory such as NAND flash and other forms Solid State Devices (SSD). NVM express (NVMe) is a new server storage I/P protocol alternative to AHCI/SATA and the SCSI protocol used by Serial Attached SCSI (SAS). Note that the name NVMe is owned and managed by the industry trade group for NVM Express is (www.nvmexpress.org).

The key question with NVMe is not if, rather when, where, why, how and with what will it appear in your data center or server storage I/O data infrastructure. This is a companion to material that I have on my micro site www.thenvmeplace.com that provides an overview of NVMe, as well as helps to discuss some of the questions about NVMe.

Main features of NVMe include among others:

• Lower latency due to improve drivers and increased queues (and queue sizes)
• Lower CPU used to handler larger number of I/Os (more CPU available for useful work)
• Higher I/O activity rates (IOPs) to boost productivity unlock value of fast flash and NVM
• Bandwidth improvements leveraging various fast PCIe interface and available lanes
• Dual-pathing of devices like what is available with dual-path SAS devices
• Unlock the value of more cores per processor socket and software threads (productivity)
• Various packaging options, deployment scenarios and configuration options
• Appears as a standard storage device on most operating systems
• Plug-play with in-box drivers on many popular operating systems and hypervisors

Why NVMe for Server Storage I/O?
NVMe has been designed from the ground up for accessing fast storage including flash SSD leveraging PCI Express (PCIe). The benefits include lower latency, improved concurrency, increased performance and the ability to unleash a lot more of the potential of modern multi-core modern processors.

Figure 1 shows common server I/O connectivity including PCIe, SAS, SATA and NVMe.

NVMe, leveraging PCIe, enables modern applications to reach their full potential. NVMe is one of those rare, generational protocol upgrades that comes around every couple of decades to help unlock the full performance value of servers and storage. NVMe does need new drivers, but once in place, it plugs and plays seamlessly with existing tools, software and user experiences. Likewise many of those drivers are now in the box (e.g. ship with) for popular operating systems and hypervisors.

While SATA and SAS provided enough bandwidth for HDDs and some SSD uses, more performance is needed. NVMe near-term does not replace SAS or SATA they can and will coexist for years to come enabling different tiers of server storage I/O performance.

NVMe unlocks the potential of flash-based storage by allowing up to 65,536 (64K) queues each with 64K commands per queue. SATA allowed for only one command queue capable of holding 32 commands per queue and SAS supports a queue with 64K command entries. As a result, the storage IO capabilities of flash can now be fed across PCIe much faster to enable modern multi-core processors to complete more useful work in less time.

Where To Learn More

View additional NVMe, SSD, NVM, SCM, Data Infrastructure and related topics via the following links.

• Use Intel Optane NVMe U.2 SFF 8639 SSD drive in PCIe slot
• NVMe overview and primer – Part I
• Part II – NVMe overview and primer (Different Configurations)
• Part III – NVMe overview and primer (Need for Performance Speed)
• Part IV – NVMe overview and primer (Where and How to use NVMe)
• Part V – NVMe overview and primer (Where to learn more, what this all means)
• PCIe Server I/O Fundamentals
• If NVMe is the answer, what are the questions?
• NVMe Wont Replace Flash By Itself
• Via Computerweekly – NVMe discussion: PCIe card vs U.2 and M.2
• Intel and Micron unveil new 3D XPoint Non Volatile Memory (NVM) for servers and storage
• Part II – Intel and Micron new 3D XPoint server and storage NVM
• Part III – 3D XPoint new server storage memory from Intel and Micron
• Server storage I/O benchmark tools, workload scripts and examples (Part I) and (Part II)
• Data Infrastructure Overview, Its Whats Inside of Data Centers
• All You Need To Know about Remote Office/Branch Office Data Protection Backup (free webinar with registration)
• Software Defined, Converged Infrastructure (CI), Hyper-Converged Infrastructure (HCI) resources
• The SSD Place (SSD, NVM, PM, SCM, Flash, NVMe, 3D XPoint, MRAM and related topics)
• The NVMe Place (NVMe related topics, trends, tools, technologies, tip resources)
• Data Protection Diaries (Archive, Backup/Restore, BC, BR, DR, HA, RAID/EC/LRC, Replication, Security)
• Software Defined Data Infrastructure Essentials (CRC Press 2017) including SDDC, Cloud, Container and more
• Various Data Infrastructure related events, webinars and other activities

Additional learning experiences along with common questions (and answers), as well as tips can be found in Software Defined Data Infrastructure Essentials book.

What This All Means

Continue reading about NVMe with Part II (Different NVMe configurations) in this five-part series, or jump to Part III, Part IV or Part V.

Ok, nuff said, for now.

Gs

Greg Schulz – Microsoft MVP Cloud and Data Center Management, VMware vExpert 2010-2017 (vSAN and vCloud). Author of Software Defined Data Infrastructure Essentials (CRC Press), as well as Cloud and Virtual Data Storage Networking (CRC Press), The Green and Virtual Data Center (CRC Press), Resilient Storage Networks (Elsevier) and twitter @storageio. Courteous comments are welcome for consideration. First published on https://storageioblog.com any reproduction in whole, in part, with changes to content, without source attribution under title or without permission is forbidden.

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