Service manual

Overview 1-5
Note these additional restrictions:
• All CPUs in a QBB must be of the same speed, because all QBBs in a GS
system operate from one common reference clock. Mixed-speed CPUs
within a QBB is an illegal configuration.
• If a QBB contains a B4125 CPU and it is replaced with a B4166 CPU, the
faster B4166 CPU will still be set to run at a slower speed with a 4-Mbyte
cache size. At the next power cycle the configuration is reassessed and
configured to reflect any new components.
• A B4166 CPU added to an empty QBB will not be configured with the
correct cache size and/or speed. This will be fixed in a future firmware
release.
• Because the power management subsystem is single-threaded (operations
are sequential), each step of the procedure must be completed before
another one can begin.
(For example, more than one CPU cannot be powered off or powered on at a
time. You can, however, issue all the commands (one command at a time
for each CPU) to take CPUs offline and power them off, then physically
remove those CPUs, and then issue the commands—again, one at a time—
to power them on and bring them online.)
Can I remove/replace the primary CPU?
No. This operation is not recommended at this time. Support for this operation
will be in a later release of the firmware. In a partitioned system, this
restriction applies to each primary CPU in each partition.
If additional CPU modules are added to a system (without
replacing others), will the operating system recognize the
new CPUs without rebooting?
Tru64 UNIX will automatically recognize the new CPUs upon insertion, even
though they are powered off. At this time OpenVMS requires that the system
be shut down, an SRM initialize command be issued; followed by the boot
command. Rebooting will not be necessary when support is added to a future
release of OpenVMS.
How does a service person determine the system environment so
he can proceed with CPU online service?
Some information must be gotten from the SRM console and the SCM monitor,
so a hard-copy record should be stored with the system. It would be helpful to