RAID Array Controller
■Each RAID set can be partitioned into smaller redundancy groups.
■The controller’s host LUN Mapping feature makes it possible to map RAID sets differently to each host port. You make the same redundancy group appear on different LUNs to different hosts, or make a redundancy group visible to one host but not to another.
■Any drive may be designated as a hot or warm spare. Spares are global, meaning that in the event of a drive failure, the controller will search for the first available spare on any channel or SCSI ID and automatically begin rebuilding the failed drive’s data.
Performance Enhancements
The controller employs a number of techniques to achieve as much performance as possible from its design.
Custom Components
To increase performance and reliability, the controller’s core functions have been encapsulated in four custom Application Specific Integrated Circuits (ASIC) components as follows:
■XOR ASIC: Used in the exclusive
■DMA ASIC: Controls the data path hardware for the various I/O ports
■CPU Interface ASIC: Supports the controller’s MIPS R3000 RISC central processing unit.
■Memory Controller ASIC: Controls the memory system and supports data movement on the internal bus at a maximum burst rate of 80 Mb/s and a maximum sustainable rate of 60 Mb/s.
