Specifications

6-24 • Configuring AlphaServer 1000A Owner's Guide

Example 6-6 The

show device

Display

>>> show device

dka400.4.0.6.0 DKA400 RRD45 2893

dva0.0.0.0.1 DVA0

ewa0.0.0.2004.0 EWA0 08-00-2B-E5-6A-41

ewb0.0.0.11.0 EWB0 08-00-2B-E1-03-19

pka0.7.0.2001.0 PKA0 SCSI Bus ID 7 2.10

On-board SCSI Bus Configuration

A fast-wide SCSI-2 controller chip connects directly to the PCI bus to support 16-bit

SCSI devices. Two connectors on the system board can be used to connect internal

devices. One connector is a 68-pin wide connector to the StorageWorks backplane,

and the second is a 50-pin narrow connector to the 5¼-inch removable-media

devices.

One 16-bit, wide internal StorageWorks shelf supports up to seven SCSI drives. The

shelf can be configured in single- or dual-bus mode. In single-bus mode, seven drives

are supported, and two of the StorageWorks slots are not used. In dual-bus mode,

two completely separate groupings of devices (three in one group, four in the other)

ensure that, if one group fails, the other continues to run.

Configuring with External Devices

When the system is configured to permit a single external SCSI device, the SCSI bus

is connected to the two 5¼-inch removable media devices. A cable (17-04233-01)

connects the bus to an external 68-pin bulkhead connector. The bus can be

terminated at this point using an external SCSI terminator, or an external SCSI cable

can be attached to connect to an external SCSI device. To meet SCSI bus length

restrictions, the maximum length of the external SCSI bus is one-half meter.

Rules for Configuring SCSI Controller Option Cards

All SCSI-2 devices are supported via EISA- or PCI-based SCSI controller cards.

Use the following rules to determine if a SCSI controller or SCSI device can be used

on your system.

The controller/device must be supported by the operating system. Consult the

software product description or hardware vendor.

In general, when configuring an 8-bit SCSI bus (narrow), up to 7 devices total

are allowed. The entire SCSI bus length, from terminator to terminator, must not