Vendors join in effort to create SSD PCIe standard

A dozen-plus vendors, including Dell, Intel, Dell and EMC, hope group can boost throughput to 2GB/sec

A coalition of top IT vendors today announced the creation of the Solid State Drive (SSD) Form Factor Working Group to create a standard that will allow manufacturers to add a PCIe interface to NAND flash products and significantly boost throughput.

The group hopes that the standard can be used by equipment manufacturers during the second half of 2011, allowing them to offer as much as 2GB/sec throughput between a computer's processor and an SSD. By comparison, SAS and SATA drives offer 6Gbit/sec and 3Gbit/sec throughput, respectively.

"We've seen storage capacity, CPU capacity and memory capacity all rising, but the storage interface has remained relatively static," said Jim Pappas, director of technology initiatives at Intel and a member of the working group. "Bringing this PCIe interface in will close that gap ... and we'll have much, much better IOPS as a result,"

The new working group is being manned by employees from most of the companies that created the PCIe standard, including Intel, Dell, and IBM. The one PCIe contributor absent from the group is Hewlett Packard.

Storage vendors EMC and Fujitsu are also part of the collaboration. SSD, controller and storage subsystem vendors, including Micron, Molex, Emulex, SandForce, FusionIO, QLogic, IDT, and Marvell, are also contributing expertise to the group.

Pappas said the working group is hoping to attract as many industry vendors as possible.

PCIe, or Peripheral Component Interconnect Express, is a serial electrical interface between a computer's motherboard and peripheral devices. Today, laptops, desktops and servers require an expansion card to use the interface, which creates an I/O bottleneck. By placing the PCIe connection pins directly onto a drive, it removes significant system overhead, according to Pappas.

"PCIe is the universal attach point. It's the closest thing you can get into the computer and memory subsystem, so directly attaching to PCIe obviously would provide the highest possible performance and lowest latency," said Pappas,.

The new standard would incorporate serial-attached SCSI, serial-ATA and PCIe all on the same drive chassis so that system manufacturers and users would not have to change their architecture to accommodate the new hardware, he added.

The group is designing the standard for 2.5-in form factor drives, the most popular size in consumer PCs, servers and many storage subsystems. There are a number of different PCIe cards and minicards available today from vendors like Dell and Asus with solid state memory.

"Interoperability is a big issue here. There's a number of PCIe solutions coming to market right now. The amount of industry investment in this area is phenomenal. But most of it is going toward a card," Pappas said. "IT knows what drives are and how to replace them. But generally shutting down a system, opening it up and replacing a card is not something they care to do."

Pappas noted that SSDs with PCIe connections could be swapped out non-disruptivly by administrators.

PCIe offers far greater throughput than SAS and SATA, neither of which can fully support the I/Os per second that a solid state drive can.

"The driving trend to even have the requirement for PCIe is based on SSDs, which drive phenomenal I/Os per second. Of course, not only are they very high performance, but they're also lower power than spinning media," Pappas said.

The working group is focused on three tasks:

  • Creating a connector specification to promote interoperability among several storage protocols, including SAS/SATA 3.0 and PCIe 3;
  • Creating a form factor that builds upon the current 2.5-inch standard to enable enclosure flexibility while supporting the new connector definition and expanding the power envelope in support of higher performance; and
  • Offering hot plug capability to create high-availability and serviceability benefits.

Work group member Gary Kotzure, a Technology Strategist with Dell, said the the standards work should be completed by the end of 2011. However, equipment manufacturers could begin using the specification to build new SSDs and systems that support them by mid-2011, Kotzure said.

The group has already completed its concept work, which includes the scope of the specification.

It will now begin working on the connector mechanics - the signals and pins - then the drive's thermal properties and mechanics and lastly the drives ability to support non-disruptive replacement, according to Kotzure.

Lucas Mearian covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at @lucasmearian, or subscribe to Lucas's RSS feed . His e-mail address is lmearian@computerworld.com.

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