User Guide

Chapter 4 RAID Configurations42
The controller, I/O, and ethernet circuit boards are assembled
into a stack with the controller and ethernet boards mounted
to a controller cover plate and the I/O board mounted to the
controller board. When the ethernet circuit board is used, it is
mounted to the controller circuit board. Figure 4-1 shows the
three circuit boards in their relative positions.
Figure 4-1 RAID Controller Circuit Boards
Features of the RAID Controller include:
• Main processor coupled with a companion chip
• Proprietary XOR engine ASIC that provides data processing XOR
function and data cache SDRAM control
• Four 2Gb-capable fibre protocol chips for the device and host ports
• Dual internal 528 MB/s, 64-bit, 66 MHz PCI buses
• Separate memory areas for processor and user data
• Scalable data cache memory: 128, 256, 512 MB DIMMs
• 128 KB NVRAM configuration memory
• Real Time Clock
• 4 MB Flash PROM
• Transparent failover/failback with multiple target ID support
The I/O circuit board includes a Battery Backup Unit (BBU) that
maintains memory content in case of AC power failure. Power for the
BBU is provided by a battery pack mounted in the fan module of the
enclosure.