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System z: Checklist for Establishing GroupCapacity Profiles

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Version 1 – March 20, 2014

ATS

Author: Pedro AcostaConsulting IT [email protected]

Co-Author: Toni SkrajnarSenior RTSC Software Specialist

[email protected]

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www.ibm.com/support/techdocs of 15Checklist for Establishing Group Capacity Profiles

Table of Contents

Introduction......................................................................................................................... 4

Step 1: Verify that initial capping (hard capping) is turned off .......................................... 5

Step 2: Creating Group Capacity Profiles........................................................................... 7

Step 3: Adding member LPARs to Group Profile .............................................................. 9

Step 4: Verify Group Capacity profile has been activated ............................................... 12

Note about Enhanced SMF recording............................................................................... 12

Summary........................................................................................................................... 13

Appendix A – Finding Operational Customization Menu on HMC Tree View............... 14



Introduction

Group Capacity enables the management of capacity for multiple z/OS LPARs on asingle CEC (central electronic complex) to a specified MSU (Million service units) limitallowing better management of CPU usage. The Group Capacity feature is available to allLPARs running z/OS V1R8 or higher.

WLM on z/OS allows management of an LPAR to a specified Defined Capacity, or softcap for LPARs using shared CPs. This value allows an LPAR to be capped when theLPAR’s capacity exceeds the set limit as judged by a rolling 4-hour average. WLM andPR/SM may apply a processor cap to ensure the capacity does not, on average, exceed theDefined Capacity. As the demand for CPU is reduced, and subsequently the rolling 4-hour average no longer exceeds the defined capacity, the soft capping function will beremoved dynamically by WLM and PR/SM. Defined Capacity cannot be defined for apartition that has an Initial Capping (hard cap) on GCPs.

A Group Capacity limit is similar to Defined Capacity, except it defines the softwareMSU limit for a group of LPARs. Capacity groups are defined at the HMC with acapacity limit in MSUs for all the members of the group. Each LPAR may be defined toonly one group. As LPARs in the group run work, their rolling 4-hour average iscalculated. If the total rolling 4-hour average for the group reaches the group capacitylimit, each LPAR is then capped to its target limit. The target limit assigned to eachLPAR is based on its LPAR weight as a percentage of the sum of the weights of allmember LPARs.

This paper describes the procedure for setting up a Group Capacity profile and assigningLPARs to become members of the group.



When you logon to the HMC you will be taken to either the Classic view or the new Treeview. These instructions will be using the Classic view. The process is very similar forthe Tree view, with a few exceptions, which are covered in Appendix A.

Step 1: Verify that initial capping (hard capping) is turned off

In order for the group capacity to take effect on your system you must first turn off initialcapping for the LPARs you will assign to the Group Capacity profile. The followinginstructions will guide this process:

In the top Views section, select Groups (1)

In the Groups Work Area section below, select Defined CPCs (2)

This will show the Defined CPCs Work Area Section. Select the desired CPC (3).

Navigate to the Operational Customization by using the navigation arrows on thelower right hand side of the screen and select Change LPAR Controls.

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Verify that the Initial Capping box is unchecked for the LPARs you wish toassign to the Group Capacity profile.

Save these changes or apply to the system by making one of the followingselections:

(1) Save to Profiles – Saves LPAR profiles onlyNote: This is not an option if you plan on dynamically making the changes to

the LPARs.

(2) Change Running System – Dynamically apply the changes to all runningpartitions. Changes are lost after a Power-On Reset is performed.

(3) Save and Change - Saves LPAR profiles and make changes to the runningsystem. Selecting this option will ensure the changes remain in effect evenafter performing a Power-On Reset.

By selecting Save and Change you have now modified the Initial Capping profile for thedesired LPARs and have dynamically changed the running system. These changes willremain even after a Power-On Reset is performed on the CEC.



Step 2: Creating Group Capacity Profiles

Now that we have verified that Initial Capping is not active for the LPARs that will bepart of the group, let’s create a new Group Capacity profile:

On the Operational Customization panel, select Customize/Delete ActivationProfiles.

On the list, uncheck the default Reset profile checkbox named DEFAULT.



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On the list you will see a Group profile also called DEFAULT. Check this profileand then click Customize Profile at the bottom of the window.

On the next screen, overtype the group named DEFAULT with your new groupname. In this example Group1 is used. Change the group description to adescription of your choice and input the desired Group capacity value in MSUs.

Click the Save button at the bottom of the window. Another window will appearasking to continue with the save; click OK to complete this process.

You have now defined your Group Capacity Profile, called here Group1, and it should bevisible in Customize/Delete Activation Profiles. You may repeat this process whendefining new Group Profiles or making changes to existing ones.



Close the Customize/Delete Activation Profiles window by selecting Close at thebottom of the screen.

Step 3: Adding member LPARs to Group ProfileLet’s now add some LPARs to the newly created group.

You should now be back on the Defined CPCs Work Area; select the desired CPC

Under Operational Customization, select Change LPAR Group Controls

You should now see the group profile you created.Select the Edit pull down menu then select EditGroup Members.


www.ibm.com/support/techdocs of15

Checklist for Establishing Group Capacity Profiles

Assign the desired partitions to your new group by typing the name of the groupin the corresponding text box. In this example we are adding three LPARs toGroup1: TOSP1, TOSP2, andTOSP3.

Click OK when done assignment ofLPARs to the group.

You should now be back on the Change LPAR Group Controls window and you shouldnow see, under the column titled Member Partitions, the LPAR names for thecorresponding group(s).

Now we have to make the changes permanent. We have three choices to accomplish this:(1) Save to Profiles – Saves the profile definitions but DOES NOT activate the Group

Capacity

Note: This option will only assign partitions to a group if the partition is currentlyinactive. Active partitions will be added to the group next time these partitions are re-activated. This option is not recommended if you want the effect to take placeimmediately.




(2) Change Running System – Dynamically implements the change to the system,however, changes will be lost if a Power-On Reset on the CEC is performed.

(3) Save and Change – Saves the changes to the profile definition AND activates thegroup capacity profile, including adding currently active partitions.

By selecting Save and Change you have now assigned LPARs to the group and havedynamically changed the running system. These changes will remain even after a Power-On Reset is performed on the CEC.

After a brief moment you will get a confirmation window displaying the status of thechange made to the Running System. Selecting OK closes the window.

The LRAPs should now be identified as part of the group. The next step will guide you inverifying the group capacity profile has been activated.




Step 4: Verify Group Capacity profile has been activated

If you dynamically activated the changes to add a capacity group you can verify itworked using RMF reports. You can use an online monitor such as RMF Monitor III tosee if the LPAR now has an active cap. In RMF Monitor III use the CPC Capacity panelto verify the changes. If the LPAR has been made part of a Group Capacity this isindicated on the top right hand corner of the screen by the Group Name and Limit asdepicted here:

Note about Enhanced SMF recording

Now that you have created and activated your Group Capacity profile, it is recommendedthat you turn on recording of SMF 99 subtype 11. If a problem should arise the SMF 99subtype 11 records would be required to do problem determination. Therefore, it isrecommended the data be collected unconditionally. Some information about this data:

The collected data is small and only written every 5 minutes Size is about 1300 bytes fixed + 240 bytes per LPAR on a CEC (Approximately

3k for a CEC with 8 partitions)




Summary

Group Capacity profiles are specified via LPAR definitions on the HMC. These profilesallow the management of CPU for a group of z/OS LPARs on a single CEC. It providessub-CEC capacity by allowing definition of LPAR capacity in MSUs with granularity of1 MSU. In order for group capacity to take effect, Initial Capping (or hard cap) cannot bedefined for the same partition. Limits are determined by using WLM’s rolling 4-houraverage in MSUs. RMF records are then used to verify and monitor the effect of groupcapacity profiles. Lastly, it is recommended that monitoring of SMF 99 subtype 11records be turned-on for systems in which group capacity profiles are implemented.




Appendix A – Finding Operational Customization Menu on HMC TreeView

On the left hand side navigation pane Click to expand Systems Management Click to expand Systems Click to highlight the CPC in question

The body of the screen will now show the tasks related to that CPC. Click to expand Operational Customization

Proceed creating the Group Profile and adding new partitions to the group by followingthe instructions discussed in Steps 1 through 4 of this guide.

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