Electronic Design

RAID Chip Combines PCI Express And SAS/SATA Drives

The single-chip BCM8603 RAID Controller Moves systems into the new world of PCI Express AND Serial drives. IDE and SCSI RAID chips are common these days, but most of them also interface to PCI/PCI-X as hard-drive technology moves to high-speed serial interfaces such as Serial Advanced Technology Attachment (SATA) and Serial Attached SCSI (SAS).

Developed by Broadcom, the BCM8603 incorporates a x4 PCI Express interface in addition to a PCI-X interface with a bridge between the two. This lets PCI Express systems use PCI-X peripherals.

The chip supports up to eight SAS/SATA drives. Each drive port supports connections up to 3 Gbits/s. SATA drives run at 150 Mbytes/s, while SATA-II and SAS drives run at 300 Mbytes/s. The BCM8603 also supports RAID01 (striping and mirroring), RAID 5, and enhanced RAID 5, including controller spanning and distributed sparing. On-chip XOR logic is used to generate RAID parity. The on-chip MIPS processor runs Broadcom's XelCore RAID software stack.

The RAID controllers can use up to 768 Mbytes of external double-data-rate memory cache. Battery backup can be used with the cache for increased reliability.

The BCM8603 costs less than $60. Broadcom also can supply the BCM8603 as a PCI-X or PCI Express adapter card. In these cases, the PCI-X to PCI Express bridge isn't utilized.

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