System Expansion; Power Control Bus For Expanded Systems - DEC 4000 AXP Service Manual

• Do not duplicate bus node ID numbers for your storage devices. For Bus E,
you can have only one storage device identified as bus node 0, one storage
device as 1, and so on.
• By convention, storage devices in the removable-media storage compartment
are numbered in increasing order from left to right, top to bottom, beginning
with zero. The TZ30, which uses internal jumper switches to assign its bus
node ID, is an exception to this rule. For ease of installation, the TZ30 uses
the default setting of five.
If you change the bus node ID plugs, you must recycle power (press the
Reset button or turn on power with the DC on/off switch) before the new
setting will take effect. The system reads the bus node ID values at
power-up.

6.1.6 System Expansion

The R400X mass storage expander provides space for up to seven additional disk
drives or up to six disk drives and a tape drive (TZ-, TF-, or TL-series). Using
R400X expanders, you can fill four SCSI-2/DSSI buses for a total of up to 28 disks
(approximately 28 GB).

6.1.6.1 Power Control Bus for Expanded Systems

The three power bus connectors on the power system controller allow you to
configure a power bus for systems expanded with the R400X expander. The power
bus allows you to turn power on and off for one or more expanders through the
power supply designated as the main power supply (Figure 6–12 and Table 6–2).
DSSI VAXcluster systems should not be configured with a power bus.
Inadvertently bringing down the cluster defeats the added reliability of a
DSSI VAXcluster.
Note
Note
System Configuration and Setup 6–23