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i/oZONE Products for the week of November 15, 2004
Broadcom Says…
RAID For The Common Man: - Broadcom's SATA-Based RAID-on-Chip
(RoC) Controller Sports Integrated PCI Express Interface
Broadcom Corporation has announced the availability of the industry's first Serial RAID-on-Chip (RoC) device that brings a level of data reliability and availability to cost- sensitive server and storage platforms that were typically available only with high-end enterprise-class storage systems. Broadcom's new RoC device is designed to be shipped as a standard offering with all classes of storage subsystems including external RAID controller cards, chassis-based servers, rack-mounted servers and blade servers.
The introduction of the industry's first Serial-ATA (SATA) RAID-on-Chip device provides a major benefit for IT professionals in the high-volume, low- end server segment requiring cost-effective RAID solutions that take advantage of low cost, high capacity SATA disk drives. The Broadcom BCM5773 RoC device combines storage processing functions with I/O bridging and advanced software technologies that enable system designers to effectively address cost and space concerns through the implementation of RAID-on-motherboard (RoMB) solutions using SATA disk drives compared to more costly multi-chip or host bus adapter (HBA) solutions.
The exponential growth of disk drive capacity has created significant reliability and performance issues for users of today's storage products that can be addressed with RAID technology. The data loss due to a drive failure continues to increase proportionally with the growth of disk drive capacity, creating ever greater needs for redundancy and data recovery.
In addition, the sustained data throughput of disk drives has not kept up with disk drive capacity growth, resulting in diminishing performance per unit of storage. While enterprise customers have adopted advanced forms of RAID technology (i.e. RAID5) to solve these reliability and performance problems, the high cost and complexity of these RAID solutions have led to limited adoption by cost sensitive customers. As small-to-medium-sized businesses (SMBs) continue to adopt SATA disk drives for storing business critical information, the requirement for cost-effective, high performing RAID solutions that boost reliability and performance becomes even more critical.
"RAID5 fault tolerance in low-end servers is an IT manager's goal, but has always been cost prohibitive. Bringing RAID5 capabilities to low-end and mid- range servers is great for cost-sensitive businesses who need highly-effective data protection," said Tony Asaro, Senior Analyst, Enterprise Strategy Group. "Broadcom is one of few semiconductor providers that can offer RAID storage to all levels of businesses, including SMBs, who can now implement enterprise- level RAID features without the cost and IT-intensive processes that have kept RAID from more widespread use."
The BCM5773 RoC device integrates several functions that previously existed as discrete components:
This high level of integration simplifies RAID on motherboard designs by reducing multiple board level components while reducing power consumption. This is achieved by eliminating multiple interfaces between discrete devices, contributing to significant cost and space savings for server and storage OEMs looking to offer enterprise-class RAID functionality to their cost-sensitive SMB customers.
Additional enterprise-class RAID functionality is provided by Broadcom's highly portable XelCore RAID software. The XelCore software provides support for all popular RAID levels, as well as enterprise-class features such as online capacity expansion, controller spanning, online RAID level migration, and the ability to create storage arrays that span multiple controllers without having to bring the system down.
"The BCM5773 RoC device, combined with the XelCore RAID software,
represents a total storage solution and introduces a powerful new paradigm
in storage I/O solution design," said Tom Marmen, Vice President and
General Manager of Broadcom's Storage Line of Business. "System designers
are now able to develop a completely new generation of server platforms,
with integrated storage capabilities for emerging high-speed serial interfaces
like SATA, while reducing design and qualification time."
analogZONE Says . . .
In my review of their BC4452-H/4852-H SATA-based RAID controller board, July 2004, I speculated on hints from Broadcom that it would likely serve as a precursor to a reference design for a "RAID-on-motherboard" solution for servers, and attached storage systems. The appearance of their BCM5773 serial RAID on-a-chip (ROC) seems to have made those speculations a reality, and in doing so, helped change the economics of storage.
Broadcom has gotten increasingly serious about the storage market over the past few years, and are now going toe-to-toe with the likes of LSI Logic, Marvell, PMC-Sierra and Vitesse. They have augmented their 2001 acquisition of the leading Intel-oriented storage chip maker ServerWorks with their 2004 purchase of RaidCORE, and are using their expertise in integration to drive storage silicon into commodity status.
A one-chip RAID controller like the BCM5773 brings cost of the electronics in RAID systems down to the scale of the new inexpensive SATA drives. When you add Broadcom's XelCore RAID software to the mix, you get the ingredients to make some extremely affordable products that put RAID-based storage within the reach of nearly any small business. I especially appreciate the fact that the controller and its software enable easy migration to higher RAID levels, something that will let the equipment be purchased at a good price point and grow with the business.
As is so often the case with Broadcom products, the controller bristles with features. It looks like all the cool features from the board-level HBA have found their way here, including the flexible sparing capability that goes beyond global and dedicated spares and enables the distribution of the spare capacity of one drive across up to eight active drives.
I won't bother to regurgitate the rest of the press release (see above) here but I will point out that the chip can be programmed to run on either PCI-X or PCI-Express host interfaces. You also get an integrated bridging option thrown in for good measure. This handy feature allows the system designer to gain extra PCI-X slots for additional I/O connectivity, when designing PCIE as the host interface.
I'll repeat my comments from the HBA review in acknowledging the flexibility of XelCore's software/hardware-independent application stack. The stack serves as a "shim" to make your application code hardware-independent. It also enables the same software to run as an application under a variety of OSs (Windows XP, 2K, 2003, plus multiple flavors of Linux), and can even be ported down to a controller card without an RTOS without changing the command interface or functionality of the controller chip. You'll really appreciate this if you've got an existing product line you want to upgrade, or have a significant investment in a particular OS platform.
The idea of a single-chip SATA RAID controller may be as revolutionary to the storage world as putting an Ethernet controller onto the mother board was for the PC by opening up a whole bunch of options for low-cost RAID-based products including network attached storage boxes and blade servers. It's also good to note that the feature-rich chip and software stack will also bring more functionality and lower cost to upper-end equipment. Things like online capacity expansion, controller spanning, and online RAID level migration will help make enterprise MIS people's life easier by letting them easily reconfigure their storage as needs change.
About the only thing that puzzles me here is the lack of serial attached SCSI (SAS) capability. While they are more expensive, many applications demand the higher performance and reliability provided by SAS disk drives. And since I have seen some SAS controllers that will also support SATA drives, I am curious about why Broadcom opted out of doing this. I have no explanation based in fact, and can only speculate that perhaps the SAS market is too immature to justify the extra complexity in an already-complex part. When pressed about this, Broadcom's answer was (and I quote), "stay tuned!" I leave it to you, the reader, to draw your own conclusions.
Reference boards for PI-X and PCI-Express are available now for early adopters. When parts are shipping they will be priced at $60 in 10-k piece lots.
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