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Server chipmakers prepare 10GbE for PCIe, virtualisation

Posted: 15 Feb 2008     Print Version  Bookmark and Share

Keywords:Server chip makers  10Gbit/s Ethernet silicon  PCIe links  virtualization standards  converged data center networks. 

Server chip makers such as NetXen Inc.and ServerEngines LLC are preparing 10Gbit/s Ethernet silicon for supporting the latest PCIe links and virtualisation standards. The devices could help boost the uptake of 10Gbit products and take servers another step down the road to converged data centre networks.

Ultimately server makers hope to be able to deliver a variety of networking, storage and clustering features on Ethernet for systems that can host multiple sessions at once thanks to virtualisation technology. But that goal is probably still more than a year away, in part because it is requiring Herculean software development efforts.

"So far no one has gotten all the pieces of the puzzle together yet," said Bob Wheeler, senior analyst at The Linley Group.

Chip developments
For example, no chip today delivers both full support for virtualisation and TCP offload engines (TOEs), used to reduce overhead on host CPUs, Wheeler said. As a crop of chips approach that goal this year, the industry will require support for yet another emerging standard to run Fibre Channel storage traffic over Ethernet.

"I don't know if we will get to one chip with everything in it, but to flesh out this converged fabric concept you need to get as much capability out there as possible, and we are still early in this effort," said Michael Krause, an interconnect specialist in the PC server group at Hewlett-Packard Co. "It's a longer period of time before you get all this in the chips in a way that's cost and power efficient," he said.

ServerEngines hopes to sample in April a new version of its 10G Ethernet chip announced in July. It will step from 2.5GHz to 5GHz PCIe links and support the single-root I/O virtualisation (SR-IOV) spec recently released by the PCI Special Interest Group to let multiple jobs share a network link.

A follow-on PCIe standard called multi-root IOV should be completed by April. It enables jobs from more than one server to share I/O resources.

ServerEngine's dual-ported chip's total throughput will rise from about 13Gbit/s to its full rated speeds closer to 20Gbit/s thanks to the 5GHz Express links. "People are dead if they don't have that," said Kim Brown, VP of business development for the startup.

The SR-IOV spec is a standard for any virtualisation software to handle sharing I/O over any network type. It will replace proprietary methods developed by server makers such as HP and IBM Corp. as well as a new network queuing technique VMWare released in its ESX version 3.5 software late last year. However full chip and software support for IOV is not expected until at least the end of the year.

Virtualisation possibilities
Analyst Wheeler said the VMWare software could be an early driver for 10G Ethernet deployments. That's because the queuing technique helps 10G devices achieve something closer to their full throughput when running the virtualisation software OEMs and end users want to get the most bang for the buck from servers.

"Virtualisation has the potential to drive 10G Ethernet adoption, but until now the products haven't had good enough performance," Wheeler said. With ESX 3.5, "now the technology becomes attractive for high-end servers," he added. ServerEngines has drivers for the VMWare software now in certification. It baked into its current 130nm chip support for 32 separate protected domains to handle virtualisation. Its next-generation 90nm part increases that to 64 domains.

NetXen expects to wait until this fall to roll out its chip supporting 5GHz Express. That's when Intel is expected to debut its first server chips sets supporting the link as part if its 45nm Nehalem family of processors.

The company claims it gets one-way throughput of about 9Gbit/s per 10G port under the latest VMWare software, although CPU utilisation levels have gone up. The drain on host processors will ease when support for the SR-IOV standard kicks in toward the end of the year, said NetXen president David Pulling.

For NetXen many of the new features are implemented in firmware on four proprietary processor cores on its chip.

"There's a tremendous amount of software and validation," said Pulling. "We are running on 1,000 servers here and with two OEMs supporting as many as 68 variations of Linux each with its own test matrix," he added.

The situation is similar at ServerEngines which has a chip using one core from ARM and eight from Tensilica. The company's first chip was completed in March 2006, but final software was not complete until last month.

"It takes that long because the amount of firmware and software is massive," said Brown. "10G is not like 1G Ethernet that was just networking. This is TOE and iSCSI and virtualisation," he added.

Storage standard
On the storage front, both ServerEngines and NetXen now support iSCSI, the standard for running SCSI storage traffic on Ethernet. ServerEngines got praise at its debut last year for handling the protocol-heavy iSCSI at data rates up to 8Gbit/s.

The iSCSI standard is seeing growing adoption, especially in small companies. However, most large companies use dedicated Fibre Channel networks for storage.

"The amount of iSCSI storage capacity is large and growing, but it is mainly at the low end and typically outside the US which is a stronghold of Fibre Channel," said Krause of HP.

The industry kicked off a standards effort last year to run Fibre Channel over Ethernet (FCoE) as part of its drive to converge all data center traffic on Ethernet. The work has been making rapid progress with the T11 standard group announcing a milestone of completing an addressing portion of the spec. A final standard for FCoE and initial chip products based on it are expected as early as the end of the 2009.

Companies such as NetXen and ServerEngines expect to rev their software again to support FCoE. The standard can require a hardware redesign for chips to optimally support all its features.

Clustering is one other requirement for some users who want to drive all traffic to Ethernet. That typically requires not only a TOE but support for the remote direct memory access standard to deliver low latency. Chip makers are at different stages in their plans for RDMA support today.

- Rick Merritt
EE Times

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