connectivityZONE Products for the week of June 26, 2006

Vitesse Semiconductor Says…
PCIe-Powered SAS RAID-On-Chip Controller Offers Multi-Tiered Solutions for Workstation, Servers, SANs
Vitesse combines RAID on demand functionality and SAS Technology in new PCI Express based SAS ROC controller family for entry-level and volume server markets


Vitesse Semiconductor Corporation has unveiled the VSC7250 and VSC7251, bringing to market the industry's most cost-effective, integrated and flexible RAID-on-Chip (ROC) solution for Serial Attached SCSI (SAS) storage. The ground breaking ROC controller ICs utilize RAID on Demand functionality to bring system vendor costs down, removing barriers for entry-level and volume server markets and accelerating the transition to next generation SAS storage. With this announcement, Vitesse completes its end-to-end SAS storage offering and reinforces its technology leadership, utilizing proven best in class SAS technology together with Adaptec's RAID expertise to create an affordable, enabling ROC solution.

"Vitesse is committed to driving technology advancement by providing cost-effective end-to-end SAS storage solutions to our OEM and ODM customers," said Tim Hornback, vice president and general manager, Storage Products Division, Vitesse. "With the Vitesse SAS RAID controller ICs, Vitesse is now offering a complete SAS product portfolio that combines interoperability, flexibility and performance to reduce overall system cost and accelerate time to market while helping entry-level and volume server markets reap the benefits of SAS storage."

RAID-on-Chip and SAS Powering Today's Complex Storage Environments
Increasing storage requirements are difficult to manage across today's complex networks. While the continuous drive for lower costs, richer functions and faster speeds move solutions in one direction, emerging needs for data integrity, protection and security pull them in another. The combination of SAS and RAID technologies meets these challenges by bringing lower costs and higher performance as well as greater scalability and reliability to higher density multi-drive systems. While providing a migration path for SCSI, the SAS technology enables a cost-effective alternative to Fibre Channel, and supports SATA storage used by small and medium businesses for its low cost and high capacity features. SAS RAID-on-Chip takes improvements one step further, allowing system vendors to utilize an integrated solution to minimize risk while simplifying system design, reducing component count and lowering costs. However, SAS RAID-on-Chip solutions to date have been designed, and priced, for high-end markets or have fallen short on performance. SAS integration also proves to be an issue with solutions offering less established SAS technologies.

Now, with the VSC7250 and VSC7251, Vitesse brings cost-effective, high performance, and reliable SAS ROC storage to entry-level and volume server markets with design attributes and functionality that underscore the company's technology leadership.

Maximum Flexibility Keeps Costs Down
The Vitesse ROC controller ICs showcase a revolutionary RAID on Demand feature for maximum RAID system design flexibility. RAID on Demand allows system vendors to use a single system design to meet various data protection requirements with a "pay-as-you-need" model that minimizes development costs and speeds time to market. Only when customers require advanced RAID feature sets will system vendors need to modify the hardware design. Additionally, Vitesse's advanced hardware-based RAID functionality unburdens the CPU to ensure performance and reliability.

Technology Leadership Reduces Risk
With the VSC7250 and VSC7251, system vendors gain a low risk SAS platform with best in class signal integrity and performance. Shipping in millions of ports today within SAS expander products, the Vitesse SAS technology utilized in the SAS RAID-on-Chip devices is well established, providing proven interoperability to minimize risk and protect data integrity. The Vitesse ROC device was also developed through partnership with SAS/SCSI expert Adaptec and is thus supported by one of the industry's most mature RAID software architectures.

"Adaptec's enterprise-class RAID solutions have been qualified and proven by major OEMs, Systems Integrators and in thousands of customer installations around the world. The combination of Adaptec RAID software with Vitesse's VSC7250 and VSC7251 controller ICs raises the bar for cost effective, high performance SAS RAID-on-Chip solutions," said Tim Connolly, vice president of marketing for the Data Protection Solutions Group at Adaptec. "In particular, the RAID on Demand feature provided by the VSC7250 and VSC7251 gives system vendors a competitive edge in utilizing maximum flexibility for cost savings in system designs and improving time-to-market."

Key RAID-on-Chip Controller IC Features
Ideally suited for RAID on Motherboard (RoMB), SAS RAID HBAs, NAS and external storage systems, the Vitesse SAS ROC solution is available in two configurations: the VSC7250 and VSC7251. The VSC7250 features eight PCI Express lanes and eight 3Gb/s SAS ports. The VSC7251 features four PCI Express lanes and four 3Gb/s SAS ports. The VSC7250 and VSC7251 are pin-to-pin compatible and at the same package size, which greatly simplifies designs.

Vitesse leverages advanced integration to help its system vendor customers reduce costs and system complexity. The Vitesse SAS ROC controller ICs offer industry leading integration, incorporating several functions that previously existed only as discrete components. These include:

 

analogZONE Says . . .

Storage is one of the current frontiers in networking and computers where there is still room for significant advances in functionality and cost/performance ratio. With even small businesses totally reliant on computers to store and serve mission-critical data, high-availability RAID-based storage systems are quickly moving from fancy luxuries to absolute necessities. And from the looks of their latest release, Vitesse is positioning itself quite nicely to take a large chunk of this market with their VSC725x PCI Express-enabled SAS/SATA RAID controller family.

Available in both four- and eight-port flavors, the controllers can support either SATA drives for lower-performance systems and fixed content (lower bandwidth) applications, or SAS drives in applications where speed and reliability are at a premium. The controller family is based on Adaptec's Radon controller chip architecture and IP, which Vitesse acquired (along with the chip's design team) a year or so ago. It integrates a 400-MHz MIPS 5Kc RISC core, a set of SAS/SATA links, and whatever else it takes to support a JBOD or RAID system (see Fig.1). A shared 128 bit 200 MHz bus provides a high-speed interconnect between all the blocks within the controller. Depending on the number of disc channels it supports, it also has either a four- or eight-lane PCI Express (PCIe) host interface.

While there are several very respectable SAS/SATA controllers already on the market from the likes of LSI Logic, PMC-Sierra - and, of course, Vitesse - this family is the first, or at least nearly the first, to include a PCIe host interface. To keep the record straight, Broadcom introduced a series of RAID-on-Chip controllers back in 2004, including one with a PCIe interface (reviewed here March 2005). But, as occasionally happens at Broadcom, the product line seems to have suffered from a series of technical and marketing problems that, at least according to my sources, has caused them to exit this market.

The Vitesse ROC has many architectural differences from the earlier Broadcom part, but it does share a similar pay-as-you-grow scheme that allows certain features and capabilities to be kept disabled unless the customer buys a key to unlock them. In its locked state, the VSC725x functions as a vanilla SAS/SATA controller that supports RAID 0/1/10 configurations without any external components except a Flash ROM (see Fig. 2).In this basic I/O-controller-mode the chip does not make much use of its on-chip MIPS core and, instead, requires an external host processor to serve as its controller. Although the off-chip control transactions do eat into performance a bit, it provides an economical solution that should be well-suited for providing basic RAID connectivity in lower-end servers and high-end work stations.

Unlocking the controller with a combination hardware/software key (Broadcom's was software-only) and adding some external memory turns it into a completely different creature. In this mode, the chip's RAID 5/6 capabilities are turned on, and I/O controller tasks are turned back over to the on-chip MIPS processor. Enabling the MIPS core eliminates the need for a separate host controller, allows for much faster transfers, and even improves RAID 0/1/10 performance. You also get an added advantage because the MIPS core uses pen-source driver code that makes for easy upgrades and, if you're brave enough, addition of custom features and functions. The external buffer memory can accept either 72-bit DDRII memory for highest performance applications or standard low-cost 16-bit memory for slower RAID 0/1/10 applications.

While the engineer in me rankles at the idea of holding a perfectly good chip's capabilities hostage like this, it does make some sense to sell a device that can be upgraded so quickly and easily. For one thing this RAID-on-demand scheme enables a single design to become multiple products at the point of sale, something that can dramatically reduce a manufacturer's inventory control and overhead costs. It also opens up the possibility of selling customers easy (and profitable) field upgrades.

Vitesse's new controller is well-positioned to take advantage of the explosive growth of the PCIe bus as the interconnect of choice within high-performance work stations and servers. Its high speed, moderate per-port cost, and ability to work seamlessly with expander chips should allow it to capture design wins in larger SAS-based storage enclosures as well.

Finally, there seems to be lots of technology here that could be easily adapted to lower-end consumer-oriented NAS/RAID products intended for home multimedia or SoHo use. While Vitesse was somewhat coy in answering direct questions about its future plans, I'd expect to see consumer/SoHo products that use these elements arriving sooner rather than later -- most likely over the next year or so.

The Vitesse VSC7250 and VSC7251 and associated customer evaluation boards are in production in both standard and Pb-free versions. Pricing for the 4-port VSC7250 and 8-port VSC7251 running in basic mode are $35 and $45, respectively. Enabling the RAID 5/6 mode is handled by Adaptec and priced separately.

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