Digital Equipment AlphaServer 2000, Owner'S Manual

Page: 128 / 196

SCSI Buses
SCSI Bus Node
IDs
When connecting devices to a bus, keep in mind that each device
on the bus must have a unique bus node ID and that you may
need to change a device’s default bus node ID in order to make
it unique. All removable-media device bus node IDs are set via
switches on the device. For information about setting a device’s
bus node ID, refer to the owner’s guide for that device.
To display bus node IDs for devices that are already connected
to your system, enter the
show device
command. Refer to
‘‘Verifying System Configuration ,’’ earlier in this chapter, for
information about interpreting the
show device
command
display.
Internal
StorageWorks
Shelves The backplane of the internal StorageWorks shelf supplies the
drive’s SCSI node ID according to the location of the drive within
the storage shelf. Each internal StorageWorks shelf can be
configured in one of two ways:
• Single bus — Up to seven drives, each with a unique node
ID. In this configuration, the bottom slot is not used.
• Dual bus — Up to four pair of drives (node IDs 0–3, top to
bottom).
The storage shelf configuration is controlled by the position of
the terminator (BA35X-MB) and jumper (BA35X-MC) as shown
in Figure 3–7 and the corresponding callouts.
!
Single Bus Configuration
"
Dual Bus Configuration
#
Bus terminator
$
Bus jumper
%
16-bit, wide SCSI bus
&
8-bit, wide SCSI bus
3–44 Options and Upgrades