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SAS Starts to ROC: Page 2 of 3

The SAS ROC controllers will also support SATA drives. One analyst says the move from parallel to serial drive interfaces is a logical place for telecom chip vendors such as AMCC, Broadcom, PMC-Sierra, and Vitesse to make their marks in storage (see PMC Still Likes Storage, Chip Trio Faces Post-Bubble Blues, and Broadcom Raids SATA Startup). Those chipmakers already have expertise with serial interfaces.

“The serial technology in SATA and SAS is similar to what has been used in telecom for years,” says Sean Lavey, IDC program manager for semiconductor research.
“Now SATA and SAS OEMs are interested in embedded solutions that would offload RAID processing.”

One of the biggest advantages of ROC designs is cost. Instead of integrating two pieces of silicon -- a RAID chip and protocol chip -- ROC requires only one. Broadcom storage marketing director Shriraj Gaglani estimates ROC can cut the price of two-chip controllers in half. ROC also reduces power consumption, and the Broadcom and LSI Logic designs allow either PCI Express or PCI-X host interfaces.

Size will also become more of an issue with a move to 2.5-inch drives for SAS and as blade severs gain in popularity. “Real estate is a big cost issue with the rise of blade servers. You can’t have multiple chips inside of a blade server,” Lavey says.

ROC is limited to servers for now. Broadcom’s Gaglani says he expects it to move into embedded storage arrays next year. That will probably happen first with SANs built for the SMB market.