User`s guide

EK–SMCPO–UG. A01 2–1
2
RAID Array Controller
This chapter describes the major features and characteristics of the RAID array control-
ler in the RAID Array 3000 subsystem. The number of devices supported by the control-
ler may be limited by the enclosure.
2.1 Controller Overview
The RAID Array controller provides high performance, high-availability access
to SCSI disk array subsystems along a UltraSCSI/Wide SCSI bus. With a modu-
lar hardware design and an intuitive configuration utility, the controller is de-
signed to meet a wide range of storage needs.
The controller consists of a single 5 1/2” x 8” PCB mounted in a sheet metal
subassembly. The package consists of the controller PCB, a 300-pin connector,
mechanical insertion assists, and an LED/reset switch interface. All signals to the
controller are routed through the backplane connector.
The unit is configured with two Ultra Wide, differential SCSI host channels ca-
pable of transferring data to and from the host at rates up to 40 MB/s. The host
SCSI IDs are configurable via the Host Parameters and can support 32 deep
tagged queuing. The controller is also configured with two Ultra Wide, single-
ended SCSI disk channels capable of transferring data to and from the disk drives
at rates up to 40 MB/s. Each channel can support up to 15 drives (14 in redun-
dant controller subsystems).
The controller has two SIMM connectors for up to 128 MB of cache memory.
The SIMM connectors form a mirrored pair when the controllers are configured
in a redundant controller configuration; otherwise they are fully accessible by the
controller. In a redundant controller setup, both controllers must have identical
cache configurations and the total usable cache (per controller) will be half the
amount installed. Thus, in a single controller setup the maximum usable cache is
128 MB while a redundant setup has a maximum usable cache of 64 MB (per
controller).