Service manual

Servicing the CPU 2-9

There are at least two factors to consider when replacing a primary CPU:

1. The desire to retain the system environment.

2. The possibility that the new CPU is at a higher or lower firmware re-

vision than other CPUs in the system.

shows the mismatch mes-

sage should the firmware differ between CPUs. Note that in this case

the newer primary has a higher firmware revision than the secondary.

The procedure described here takes these into consideration.

After you have removed and replaced the defective primary CPU following

the instructions in Chapter 1, take the following steps:

1. Power up the system. If self-test fails, refer to the appropriate Ad-

vanced Troubleshooting manual; otherwise continue.

2. Note the firmware revision of the new CPU.

3. Use the set cpu command to connect the console terminal to another

CPU in the system.

4. Use the update -e command to copy the EEPROM environment vari-

ables from the secondary processor to the new primary processor.

(The update -e command copies the system serial number and other

parameters that can be set, as well as any additional information

stored in the EEPROM to the target CPU.)

5. If there is a firmware revision mismatch, you should update the

FEPROMs on the older CPUs. To do this, run the console on the

newer CPU. Use the set cpu command to get to the newer version

and then use the update -f command. Note that if there are several

CPUs that need updating, you can use a wildcard to target them all,

as in update -f kn7aa*.

6. Use the set eeprom field command to enter the 8-digit LARS number

and a short message (up to 68 characters), stating the date and reason

for service, into the EEPROM.

7. Boot the system and return control to the customer.

NOTE: If the customer used the set cpu_primary command to change the

default which allows all CPUs in the system to become the pri-

mary, the set cpu command may not work.

To allow all CPUs in the system to become the primary processor, use the

set cpu_primary ff command. Modify the cpu_primary environment

variable to the customer setting after performing the updates.