Removing a CPU on P5 system.

[Mag0007]

On a P5 system, does removing a CPU need a reboot? or is it all dynamic?

tia

 

[BocaBurger]

How are you removing it?



BocaBurger
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The pen is mightier than the sword, but the sword hurts more!

 

[Mag0007]

I am doing it via HMC.

 

[p5wizard]

You mean unassigning a CPU from an LPAR? That is dynamic, as long as you don't go below the minimum CPU setting for that LPAR. For AIX52 DLPAR or AIX53 DLPAR you add/remove whole CPUs. For AIX53 SPLPAR you tweak the CPU entitlement, the number of virtual CPUs, the Capped/Uncapped setting and possibly the UncappedWeight.

Physically removing/replacing a CPU card on a p5 is not a customer task and involves a serious downtime.


HTH,

p5wizard

 

[Mag0007]

So, dynamically removing it does NOT require downtime?

Sorry for being dumbb

 

[p5wizard]

That's the whole idea of it being a DLPAR - Dynamic LPAR - i.e. you don't have to reboot an LPAR to take away or add a CPU. Provided you set the minimum and maximum number of CPUs for an LPAR to min=1 and max=(the number of CPUs in the system), you can do pretty much what you like with the CPU allocation for that LPAR.
Of course you don't want to take away 6 CPUs from a running 8way database server LPAR which has some 1000 users online...


HTH,

p5wizard