Service manual

System Overview 1-41
Service can be performed on one or more partitions while other partitions
remain operational. Once the operating system running in a given partition is
shut down, power can be removed from the partition without removing power
from other partitions. And once a QBB is in an Off state, any module in that
QBB can be replaced or added without further disruption of the system.
Rules for Servicing Partitions
1. Only hard partitions can be powered off.
2. If a hard partition or system is soft partitioned, each instance of the
operating system in each soft partition must be shut down before the
hart partition or system is powered off.
3. Once the partition is powered off, put the service switch on the PSM(s)
in the QBB(s) that define the partition in the Service position. This
prevents both a remote user from powering on the QBB/partition while
it is being serviced and a partition power-on should a master SCM
failover to a backup, master-eligible SCM.
Example 1–1 shows how a partition can be shut down. The general procedure
consists of the following:
Shut down the operating system in the partition.
At the SRM console prompt, enter the power off command. This
command causes all activity throughout the QBB/partition to cease and
then power off to occur. Using the SCM power of –par x command takes
power away from the QBB/partition with out cleanly stopping the
partition’s activity.
The hard partition and its configuration is identified and power down
starts.
The SCM command show csb is issued here to show the result of the SRM
power off command.
The SCM command show csb shows that the service switch on the PSMs
in the QBBs powered off has been switched to Service. See Section 1.8.4
for a functional description and Section 1.12 for a physical description of
the PSM.