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How to disable one Core of CPU

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Bob Fraser
Occasional Advisor

How to disable one Core of CPU


I am running into a licensing issue with one of my sofwtare suppliers.

How do I disable one core on a cpu
My map looks like this:

CPU Information:
Number of CPUs in the system = 2

cpu -----------------------------------------
slot | 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 |
state|caM |ca | | | | | | |
| 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 |
state| | | | | | | | |
c - Configured (CPU powered on)
d - De-configured (CPU powered off)
a - Active (configured and processes running)
i - Inactive (configured and idle)
f - Inactive with fail (inactive because of a CPU failure)
M - Monarch CPU (always Active)
C - Marked for re-configuration (Configured after next boot)
D - Marked for de-configuration (De-configured after next boot)

Any help would be appreciated.

Thanks in advance.
Acclaimed Contributor

Re: How to disable one Core of CPU

Commands are different for different platforms.

Usually you can disable a complete CPU, but not single cores.


Main Menu: Enter command or menu > co

---- Configuration Menu ------------------------------------------------------

Command Description
------- -----------
AUto [BOot|SEArch|STart] [ON|OFF] Display or set specified flag
BootID [] [] Display or set Boot Identifier
BootINfo Display boot-related information
BootTimer [0 - 200] Seconds allowed for boot attempt
CPUconfig [] [ON|OFF] Config/Deconfig processor
DEfault Set the system to predefined values
FastBoot [ON|OFF] Display or set boot tests execution
PAth [PRI|ALT] [] Display or modify a path
SEArch [DIsplay|IPL] [] Search for boot devices
TIme [c:y:m:d:h:m:[s]] Read or set the real time clock in GMT

BOot [PRI|ALT|] Boot from specified path
DIsplay Redisplay the current menu
HElp [] Display help for specified command
RESET Restart the system
MAin Return to Main Menu
Configuration Menu: Enter command >

Hope this helps!

There are only 10 types of people in the world -
those who understand binary, and those who don't.

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Honored Contributor

Re: How to disable one Core of CPU

What is the server model?
Use command 'model'

The CPU type installed?
How this is determined depends on the OS:
- 11.11/.23 - SAM -> Performance Monitors -> System Properties.
- 11.31 - use command 'machinfo'

As stated cores cannot be deconfigured, only CPU modules. However, with the above info we may be able to assist you further!

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Bob Fraser
Occasional Advisor

Re: How to disable one Core of CPU

From SAM!


Active: 2
Total: 2
CPU Version: PA 8800 CPU Module 3.1
Clock Frequency: 1000 MHz
Machine Identification: 1039716969
Hardware Model: 9000/800/rp3440
Kernel Width Support: 64
Honored Contributor

Re: How to disable one Core of CPU

OK, so I can confirm that you cannot simply deconfigure one of the cores. An attempt to do so will try to deconfigure both cores on the CPU module. In the case with only 1 CPU module installed, the attempt will simply fail.

In order to have your system register as a 1 way server, you need to have your model string adjusted to read 'rp3440-1' (or similar). This is possible, but requires an HP engineer onsite to do this. Another option is the use of the "downgrade" command from the BCH Service Menu. However this typically only works if your system was once upgraded.

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Dennis Handly
Acclaimed Contributor

Re: How to disable one Core of CPU

Hmm, I wonder if software like ICAP may help?
Unfortunately it doesn't seem to support rp3440.
What HP-UX version are you using?