z/OS Assignment of Logical CPs to Physical CPs
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#1: z/OS Assignment of Logical CPs to Physical CPs Author: bay hoe san PostPosted: Fri Aug 27, 2010 3:15 am
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Hello,

I need expertise advice on
--> how to assign logical CPs to physical CPs in a zOS machine, say a 2064-1C8 with 1621 MIPS, use what method and how?
--> after assignment how to check?

Pls advise.
Thank you.

.Hoe San.

#2:  Author: taltymanLocation: Texas PostPosted: Sat Aug 28, 2010 4:41 pm
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I'm not clear on what you are asking. Do you mean assign CPs to an LPAR?

#3:  Author: bay hoe san PostPosted: Sun Aug 29, 2010 7:37 pm
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Hello,

Thanks for your response.
Apologize. Allow me to rephrase my query:
Qns: Say, we have a machine 2064-1C8 with 1621 MIPS and having 8 physical CPs. We have 3 LPARs i.e. LP1, LP2 and LP3 in a parallel sysplex.
How many MIPS is each CP?
How to assign 800, 500 and 321 MIPS to LP1, LP2 and LP3 respectively?
Are we being to allocate MIPS on the fly?
Can we create 12 logical CPs? If so, can we map 12 logical CPs to physical CPs (guess, the MIPS allocation will change)?

Pls advise.
Thank you.

.Hoe San.

#4:  Author: taltymanLocation: Texas PostPosted: Mon Aug 30, 2010 7:40 am
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The easiest way to accomplish most of your goal is to use the HMC. Logon to your HMC. Double click the Groups icon. You should then see CPC images and Defined CPCs. Images are your lpars and CPCs are the physical CECs or processors. Double click on Defined CPCs and it should show you each CEC or CPC. Now either use the right side of the screen and find the Change LPAR Controls option or right click the CPxx icon to see the drop down and select Operational Customization and then select Change LPAR Controls. This will bring up a screen that has all the lpars that are available to that CPC and a place to enter values. I'd suggest either making the weights all add up to your 1621 mips or to a number that can be used to figure percentages such as 1000. In you case you could have them all add up to 1621 and give LP1 a weight of 800, LP2 500 and LP3 321. That basically reserves those mips for the respective lpars. If any lpar is not using its weight then those cycles are free to be used by the other lpars. Unless you have to cap lpars there's no point in letting cycles go to waste.

Then select Save and Change Running System to dynamically adjust weights on your running lpars.

#5:  Author: bay hoe san PostPosted: Thu Sep 02, 2010 2:01 am
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Hello,

Greatly appreciate your responses, I have benefitted.
I take reference with my e.g. of a 2064-1C8 with 8 physical CPs.
1. I heard people saying assign logical CP. Do they mean in HMC we can have logical CPs defined? If so, how logical CP map to physical CP?
2. Say 2064-1C8 is being partitioned into 4 regions e.g. LP1, LP2, LP3 and LP4 with weightage 640, 245, 80 & 35 respectively.
Questions:
1. are we able to know the physical CP that map to the above weightage?
2. are we able to know the logical CP that map to the above weightage?
3. when I do a /d m=cpu, I noticed the following:
In LP1, display 6 CPs,
In LP2, display 5 CPs,
In LP3, display 2 CPs and
In LP4, display 3 CPs.

I would suppose the above is logical CP, isn't it? How is the assignment being done? Via HMC or sys adjust itself base on weightage?

Pls advise. Thank you.

.Hoe San.

#6:  Author: taltymanLocation: Texas PostPosted: Thu Sep 02, 2010 3:15 pm
    —
I'll make a valiant attempt to answer but you should talk to your sysprogs for clarification for what they've done and why at your shop.

1. I heard people saying assign logical CP. Do they mean in HMC we can have logical CPs defined? If so, how logical CP map to physical CP?

I'm not sure of a way to map a logical CP to a physical one.

2. Say 2064-1C8 is being partitioned into 4 regions e.g. LP1, LP2, LP3 and LP4 with weightage 640, 245, 80 & 35 respectively.

Questions:
1. are we able to know the physical CP that map to the above weightage?
No
2. are we able to know the logical CP that map to the above weightage?
No
3. when I do a /d m=cpu, I noticed the following:
In LP1, display 6 CPs,
In LP2, display 5 CPs,
In LP3, display 2 CPs and
In LP4, display 3 CPs.

Not sure why you are worrying so much about physical to logical mapping but...
LP1 is assigned a 64%, LP2 24.5%, LP3 8% and LP4 3.5% of the total MIPS. So this would be the normal weighting but LPARS could use less or more depending on what is being used by the other LPARS. Unless they are capped which would restrict them from using more.

Next you notice that not one lpar is assigned all 8 CPs.
Depending on your applications some application prefer more CPs and some can't benefit much from more CPs being assigned.
They could have all just as easily been assigned 8 CPs.

I would suppose the above is logical CP, isn't it?

Yes

How is the assignment being done? Via HMC or sys adjust itself base on weightage?

The 'system' does not add or remove logical CPs based on assigned weight. As I recall it's done via HMC.



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