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SSD drives promise to enhance storage performance, but a new host-interface-standard holds the key

By Kam Eshghi, special to Network World
August 08, 2011 02:51 PM ET

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Indeed, the NVMe standard will ultimately deliver plug-and-play functionality for PCIe-connected SSDs. The NVMe 1.0 specification, developed cooperatively by more than 80 companies from across the industry, was released in March 2011 by the NVMHCI Work Group -- now more commonly known as the NVMe Work Group.

The specification defines an optimized register interface, command set and feature set for PCIe SSDs. The goal is to help enable the broad adoption of PCIe-based SSDs, and to provide a scalable interface that realizes the performance potential of SSD technology now and into the future. The NVMe 1.0 specification may be downloaded from www.nvmexpress.org.

The NVMe specification is specifically optimized for multi-core system designs that run many threads concurrently with each thread capable of instigating I/O operations. Indeed, it's optimized for just the scenario that IT managers are hoping to leverage to boost IOPS. NVMe specification can support up to 64k I/O queues with up to 64k commands per queue. Each processor core can implement its own queue.

In June 2011, the NVMe Promoter Group was formed to enable the broad adoption of the NVMe Standard for PCIe SSDs. Seven industry leaders will hold permanent seats on the board: Cisco, Dell, EMC, IDT, Intel, NetApp and Oracle. Six other seats will be elected from companies who are members of the NVMHCI Work Group.

There is still work to be done before NVMe becomes a mainstream technology, but the broad support among a range of industry participants virtually guarantees that the technology will become the standard for high-performance SSD interconnects. Supporters include IC manufactures, flash-memory manufacturers, operating-system vendors, server manufacturers, storage-subsystem manufacturers and network-equipment manufacturers.

Over the next 12 to 18 months, expect the pieces to fall in place for NVMe support as drivers will emerge for most popular operating systems. Moreover, companies will deliver the SoC enterprise flash controllers required to enable NVMe.

Form factors for PCIe SSDs

The NVMe standard does not address the subject of form factors for SSDs and that's another issue that is being worked out through another working group.

In enterprise-class storage, devices such as disk drives and SSDs are typically externally accessible and support hot-plug capabilities. In part, the hot-plug capability was required due to the fact that disk drives are mechanical in nature and generally fail sooner than ICs. The hot-plug feature allows easy replacement of failed drives.

With SSDs, IT managers and storage vendors will want to stay with an externally accessible modular approach. Such an approach supports easy addition of storage capacity either by adding SSDs, or replacing existing SSDs with more capacious ones.

Indeed, there is another standards body that has been formed to address the form factor issue. The SSD Form Factor Working Group is focused on promoting PCIe as an SSD interconnect. The working group is driven by five Promoter Members including Dell, EMC, Fujitsu, IBM and Intel.

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