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Offlining a CPU

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Steve Wilde_1
Occasional Visitor

Offlining a CPU

Hello All - I have a GS140 (8400) with four CPU's, 0, 1, 2, 3. I would like to off-line CPU 3 to prevent it from being used. The system is at the console prompt. When I tried to set the cpu_enabled setting to fff7 I could no longer access my hard drives. Can somebody help me? Thanks.
5 REPLIES
Michael Schulte zur Sur
Honored Contributor
Solution

Re: Offlining a CPU

Hi,

my idea would be set cpu_enabled 7

Michael

the origin for that is the following note in the readmes for v6.6 firmware

For example changing cpu_enabled, on a four-CPU system, from F to 0 will disable cpu1-3
Hein van den Heuvel
Honored Contributor

Re: Offlining a CPU

WHY do you want to offline a CPU? Aplication (license) pricing?

I would try to avoid changing the mask because it needs a reboot to undo. If you can get away with it, just use 'offline 3' or 'psradm -f 3'. Of course if that might not make the legal requirements...

I would also opt for mask '07'. btw... are the CPU tightly packed from the right front?

I don't understant how disabling a (non-primary) cpu would prevent access to the hard drives ?! What does show dev/ show config tell you at the P00>>> prompt ?
You did not accidently reboot from a different boot disk/file by accident? (show boot_def_dev or show boot*)

Also... which version/patchlevel of Tru64 ?

fwiw,
Hein.



Mohamed K Ahmed
Trusted Contributor

Re: Offlining a CPU

From the SRM console you can disable CPU 3 by setting the cpu_enabled to 7. Probably it is set to ff or f now

P000> show cpu_enabled
P000> set cpu_enabled 7
P000> boot

Mohamed
Steve Wilde_1
Occasional Visitor

Re: Offlining a CPU

Well, I wanted to offline it because I'm getting KMF's on CPU3 & I don't have support on the thing. I only need two CPU's for my application.

I know that setting the CPU mask shouldn't affect seeing disks but when I leave the mask at ffff (where it was by default) I can boot to my disks and when I change it to fff7 I can see the drives with the sho dev but when I try to boot to any of them I get a message saying the drives are no longer valid. Maybe this is a seperate issue though.

I don't have a valid O/S on it right now (it corrupted during an LSM mirror function when CPU3 KMF'd. I can boot the image but the root domain is corrupted.) I do have firmware 6.3 on though.

Thanks for the help. -Steve
Mohamed K Ahmed
Trusted Contributor

Re: Offlining a CPU

the cpu_enabled is a hex number
CPU # ( 1=enabled, 0=disabled)

1 2 3 4 CPU_ENABLED
1 0 0 0 = 1
1 1 0 0 = 3
1 1 1 0 = 7
1 1 1 1 = f or ff or ffff it doesn't matter

So to disable CPU 3 and enable CPU 0 , 1 and 2, you have to set the cpu_enabled to 7

Mohamed