Transcript Group Capping

Saving Software Costs
with Group Capacity
Richard S. Ralston
May 13, 2010
OHVCMG
Abstract/Topics
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What are Group Capacity Limits?
Benefits of Group Capacity Limits
How to define a group and its limit
Determining where to set the group limit
When are group limits in effect?
Real-time Monitoring of Group Capacity Limits
Impacts of running under the group limit
Financial benefits of using group limits
What are Group Capacity Limits?
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A Group Capacity Limit is similar to LPAR Defined
Capacity except it defines the Software MSU Limit
for a group of LPARs.
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Identifies the billing point for the group.
When the 4 hour rolling average exceeds the Group
Capacity Limit, CPU resource is limited to the Group
Capacity Limit
The grouped LPARs must all be on the same CEC.
They (the LPARs) may span sysplexes.
z/OS 1.8 or higher
z9 or z10
Benefits of Group Capacity Limits
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Better control of your VWLC software cost
Better sharing of CPU resource amongst LPARs
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LPAR with greater need can use CPU resources that a
LPAR Defined Capacity would prevent.
LPAR(s) not using CPU resource ‘gives it up’ for the
LPAR(s) needing them.
May choose to eliminate LPAR Defined Capacities
and have fewer control points to tweak.
How to Define a Group and Its Limit
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Done at the HMC.
SC28-6860-01 System z9 Support Element
Operations Guide
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Defining a group, page 6-40
Changing Group Capacity Limit, page 9-4
SC28-6868-00 System z10 Enterprise Class Support
Element Operations Guide
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Defining a group, page 6-41
Changing Group Capacity Limit, page 9-4
Determining Where to Set the Group
Capacity Limit
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Fast answer 1 - sum of your LPAR Defined Capacities
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Fast answer 2 – 3% Below your current SCRT MSU billing
amount (sum of the LPAR Defined Capacities)
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Turn off LPAR Defined Capacities
May turn off LPAR Defined Capacities
Up to 10% may be easily acceptable/achievable when starting
Monitor your system usage and the 4 hour rolling averages
and use some finesse to determine the Group Capacity Limit.
When adding a zIIP or zAAP you can reduce the Group
Capacity Limit by the amount of CPU resource you will
move to the zIIP or zAAP.
The same rules about when to set LPAR Defined Capacity
apply to Group Capacity Limits.
SYSDLAC
SYSMLAC
Time
SYSSLAC
Propose reducing the Group Capacity Limit from 1475 to 1450.
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0
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SW MSUs
Monitor & Finesse
SW MSU 4HRA
LDC1
SYSDLAC
SYSMLAC
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SW MSUs
Monitor & Finesse - Results
SW MSU Usage
LDC1
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Time
SYSSLAC
This reduction of 25 Software MSUs had little impact on the duration of time running
under the Group Capacity Limit.
Determining Where to Set the Group
Capacity Limit – Exercise
1
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Moving test CICS, DB2, IDMS and
associated batch from an LPAR on LDC1 to a
new LPAR on LDC2
The LPAR will be 300-580 SW MSUs
Need to add 3 CPs to the machine
Need to determine the new Group Level
Capacity
Determining Where to Set the Group
Capacity Limit – Exercise
2
LDC2 LPARS
1800
1600
1400
SW MSUs
1200
2097-717 - 1321 SW MSUs
2097-714 - 1139 SW MSUs
1000
800
600
400
200
Hour of Day
SYSAMSU
SYSFMSU
SYSHMSU
SYSIMSU
New SYST
What size machine do I need with the new Workload?
08APR09:21:00
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0
Determining Where to Set the Group
Capacity Limit – Exercise
3
LDC2 LPARS
1800
1600
1400
SW MSUs
1200
2097-717 - 1329 SW MSUs
New Group Capacity
1000
Current Group Capacity
800
600
400
200
Hour of Day
SYSAMSU
SYSFMSU
SYSHMSU
Where do I set the Group Capacity Limit?
SYSIMSU
New SYST
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When Are Group Limits in Effect?
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When the sum of the 4 hour rolling averages for the
LPARs in the group is greater than the Group
Capacity Limit.
All the LPARs in the group show that they are
running under the ‘cap’ at the same time.
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Capping percentage for all LPARS > 0
On a z10 with hiperdispatch I have observed some
periods (minutes) with one or more LPARs not
capped and yet the overall group is capped.
Reporting
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The RMF Postprocessor Group Capacity
report reports after the fact.
SAS along with MXG or MICS
z/OS TDS
Other home grown reporting
The IBM Sub-Capacity Planning Tool and
your favorite spreadsheet software
Group Capacity Limit Reached
1
Group Capacity Limit Reached
2
Capping Percentage
1
Capping Percentage
1
Real-time Monitoring of Group
Capacity Limits
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There are no good tools that I am aware of.
Need to sum the 4 hour rolling averages for each LPAR in the
group and compare the sum against the Group Capacity
Limit.
Best I’ve found so far: RMF PM
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Display the %WLM Capping for each LPAR
Display the 4 Hour Rolling Average for each LPAR
2nd Best – Customized View in RMF Data Portal
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Free RMF/Browser tool – built into RMF Monitor III
IP Address: http://nnn.nnn.nnn.nnn:8803/
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nnn.nnn.nnn.nnn is the IP address of LPAR running GPMSERVE
ftp://ftp.software.ibm.com/eserver/zseries/zos/rmf/RMF_MonitorIII_
DataPortal.pdf
The Group Capacity Limit is not a displayable field with
these tools.
Sample RMF PM Display
Impacts of Running Under the Group
Capacity Limit
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LPAR Weighting Factors are Important!
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WLM Class definitions and Policy are Important!
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Weighting Factors not only determine LPAR dispatching
priority, but the percentage of the machine the LPAR gets
when under the Group Capacity Limit.
Important work in a small LPAR may need a higher
Weighting Factor than the algorithm(s) indicate.
Lower priority work may suffer if the Group Capacity
Limit is too low.
If an LPAR is scrunched too far by Group Capacity
Limits
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Batch (lower priority work) will take longer
Online response time may suffer
Financial Benefits of Using Group
Capacity Limits
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You can lower your VWLC software cost by using
Group Capacity Limits.
Determine your incremental software cost, $/MSU
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Savings = $/MSU * MSU Reduction
Example:
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Need 2 consecutive months bill
$/MSU = (m2$-m1$) / (m2msu-m1msu)
Savings = $300 * 25 = $7500/month
Your results will vary.
What’s Next?
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Automatically changing Group Level
Capacity through the HMC API.
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Lower Group Level for non-Prime hours.
Prevent SW bill from being set during non-Prime
time.
Article for zJournal
Thanks
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Kelly Vogt - Humana
Al Sherkow - I/S Management Strategies,
LTD.
Myron Highfield - IBM
Questions/Discussion
Thank You!
Contact Info
Richard Ralston
[email protected]
[email protected]
[email protected]