HP NetRAID Installation and Configuration Guide

Chapter 1 Introduction
5
Adapter Hardware and Battery-backed Cache
IOP: The I/O processor (IOP) directs all functions of the adapter, including
command processing, PCI and SCSI bus transfers, RAID processing, drive
rebuilding, cache management, and error recovery.
• The IOP for the HP NetRAID-3Si adapter is the 32-bit Intel i960RD
®
Intelligent I/O RISC processor running at 66 MHz.
• The IOP for the HP NetRAID-1Si adapter is the 32-bit Intel i960RP
®
Intelligent I/O RISC processor running at 33 MHz.
ASIC: A custom ASIC (Application Specific Integrated Circuit) provides PCI
bus mastering with a burst data transfer rate of 132 MB/sec. The ASIC handles
data transfer between the PCI bus, the cache, and the SCSI bus. This ASIC
supports memory write and invalidate commands on the PCI bus. It also performs
RAID mirroring, parity generation, and checking in RAID levels 1, 3, 5, 10, 30,
and 50.
Cache: All HP NetRAID Series adapters have cache memory.
• For the HP NetRAID-3Si adapter, cache memory resides in a 16-MB
battery-backed 60-ns EDO (Extended Data Output) DRAM SIMM. You
can replace this SIMM with a 64-MB EDO DRAM SIMM.
• For the HP NetRAID-1Si adapter, cache memory resides in a 16-MB
60-ns EDO (Extended Data Output) DRAM SIMM.
The HP NetRAID Series adapters support Direct and Cached I/O and Write
Through or Write Back caching, which can be selected for each logical drive. To
improve performance in sequential disk accesses, the HP NetRAID Series
adapters use Adaptive Read Ahead caching by default, but it can be disabled to
Normal or set to simple Read Ahead caching.
Alarm: The HP NetRAID Series adapter’s onboard tone generator provides
audible warnings (alarms) when RAID system errors occur.