User`s guide

11. HSZ Array Controllers: Set preferred paths to balance the load and
improve the performance of your HSZ array controller as follows:
After setting the total number of SCSI target IDs for the pair, set the
preferred IDs to define which targets will be assigned to each controller.
Enclose the target numbers in parentheses and separate each target number
by commas as follows:
CLI> SET THIS_CONTROLLER PREFERRED_ID= (n,n)
CLI> SET OTHER_CONTROLLER PREFERRED_ID= (n,n)
You may only specify the preferred IDs that were first set with the
SET THIS_CONTROLLER ID= and SET OTHER_CONTROLLER ID=
commands. A maximum of four IDs may be specified in any combination
between the two controllers. If two or more PREFERRED_IDs are set,
enclose the IDs in parentheses and separate each ID number by a comma.
When you change the preferred IDs on one controller in the pair, the other
controller is automatically updated to the remaining (if any) IDs.
12. HSZ Array Controllers: Use the NOPREFERRED_ID= qualifier if you
decide not to set preferred IDs as follows:
CLI> SET THIS_CONTROLLER NOPREFERRED_ID
or
CLI> SET OTHER_CONTROLLER NOPREFERRED_ID
By specifying the NOPREFERRED_ID qualifier, the controller with
NOPREFERRED_ID set does not respond to any target ID on the host’s
SCSI bus. However, in a dual-redundant configuration, if the controller with
PREFERRED_ID set fails, the controller with NOPREFERRED_ID set takes
over the targets of the failed controller.
13. (All controller models:) Connect internal and external host port cables,
trilink connector blocks, and terminators as applicable. Refer to the
appropriate sections in Chapter 4 for instructions for making these
connections.
CAUTION
For HSD30 array controllers:
Unless you have a mating guide (refer to Chapter 4) installed on the
HSD30 controller’s host port connector, you must turn off all power to
HSD30 controllers and all other devices, including the host CPU, on a
DSSI bus before connecting or disconnecting a DSSI host port cable.
Without the mating guide, if you accidentally short DSSI connector pins
during aligning and connecting/disconnecting the connector, you risk
blowing the fuses of all members of the DSSI bus.
With the mating guide installed, you may disconnect or connect the
DSSI host port cable connector with power applied to the controller and
other members on the host bus. However, Digital recommends carefully
connecting or disconnecting the DSSI connector at all times, even if you
have the mating guide installed.
Some DSSI host port cable connectors are too large to allow access to the
trilink connector screws. You must remove the trilink with the host port
5–14 Controller Operations