AIX

@bakunin - I apologise for short term words,

And this is what the concept i missed, I understand a bit what you mean(Red book confused me)

In NMON i could see the CPU usage was 120% , it means it taking some resources from shared pool.

But could you please brief me more like , how much limit an capped LPAR can share thier idle resources to shared pool and also how to find the available resources residing in shared pool.


Thanks,
Thala

For capacity planning NMON is not the ideal tool. I suggest giving LPAR2RRD a try (which is available freely too) or Ganglia (OS software and free).

OK: basically, for CPU and memory, there are 3 values: minimum, desired and maximum. "Minimum" is what the LPAR needs at all cost, without that it won't start. "Desired" is what it gets if there are no other constraints. "Maximum" is what it can allocate at the upper limit.

Now, "capped" means that such a maximum is in place. "uncapped" means there is no maximum value and the LPAR can allocate whatever it needs.

The art of capacity planning is to find sensible values for these attributes. If you set the minimum too low you burden the system with swapping around resources very oftenly, which will be bad for overall performance. If you set minimum values too high you lose flexibility and the system is less free in redirecting the resources where they are needed most.

Finding out what "sensible" values are is a complicated task which requires experience and knowledge about load characterstics of the applications involved. A general answer is hard to give.

I suggest studying the Redbooks nevertheless, they are very well written (even if their merit becomes notable only on second view). I suggest to read and study the characteristics of the POWER processor too, especially terms like SMT, cache usage virtual/logical/physical CPUs/cores should help you understand better the workings of your p5xx/p7xx system.

I hope this helps.

bakunin

Everything that we've told you about donating unused cycles still holds true for Capped LPARS, the only real difference is that a Capped LPAR. Isn't allowed to exceed its Entitled Capacity.

NMON running an all the LPARs with the Consolidator spreadsheet for analysis is a good way to see how the CPU is being used across the system.

One more last clarification , post that this discussion can be closed.

&

So based on both statements, It means Capped LPAR can share their resources to Shared Pool but it cant get some CPU from Shared Pool when it was needed.
Whereas uncapped can share as well as get resources in pool?



Thanks,
Thala

Close, but not quite. In normal circumstances a capped LPAR (as well as an uncapped one) will get the "desired" value. If resources are available both will get more if they need it, but a capped LPAR will stop at "maximum", whereas an uncapped LPAR will get even more beyond this point.

I hope this helps.

bakunin