Understanding CICS performance on z/OS

 Check out https://www.youtube.com/playlist?list=PLezLS0Tuqb-5vZaePphy1MMyOTBUINqpn

Vides with following title can be found in the above link

CICS Performance 101: Introduction

CICS Performance 101: Session 1 - Making Sense of MIPS

CICS Performance 101: Session 2 - Making Sense of MSUs and SUs

CICS Performance 101: Session 3 - Making Sense of ITR

IBM Z Software Pricing

 Checkout https://www.youtube.com/playlist?list=PLezLS0Tuqb-4GIwmKe7pOUU8AT4h7v-ul

Below topics are covered

zSoftware Licensing Terms and Conditions
IPLA Software Terms and Conditions
Multi-Version Measurement (MVM)
Parallel Sysplex Aggregation
On/Off Capacity On Demand (OOCoD)
Backup, Disaster Recovery, and Capacity Backup Upgrade
zNALC and MzNALC
VUE Program Licensing Calculations
Cross Systems Waivers
Per Payments Pricing on z/OS
Container Pricing for IBM Z
Mobile Workload Pricing
Country Multiplex Pricing
z/VM and Distributed Linux Middleware on Z
Defined Capacity and Group Capacity Limits
Sub-Capacity and Rolling 4 Hour Average
Reading the SCRT Report
Workload Pricer Support for S&S Anniversary Dates
Advanced Entry Workload Pricing

How Tivoli Decision Support for Z/OS reports 4HRA

 Tivoli Decision Support for Z/OS leverages the SMF data to provide a variety of reports for various components of System Z. TDS maintains a database for different SMF record types which can be queried using QMF to provide reports on the fly. One such report is the monthly 4 hour rolling average report for each LPAR in the CEC. TDS provides ‘MVSPM_SYSTEM_H’ and ‘MVSPM_LPAR_H’ tables which contains the ‘MSU_4HRA’ (SMF70LAC) for each LPAR in the CEC. The below section establishes a reporting technique which will align with the SCRT report.

USING MVSPM_LPAR_H 

‘MVSPM_LPAR_H’ provides hourly statistics on logical partitions and processor activity in a PR/SM environment. It contains data from SMF type 70. The ‘MSU_4HRA’ column contains the 4-hour rolling average for each logical partition. This value ‘MSU_4HRA’ in table ‘MVSPM_LPAR_H’ is the last effective 4 hour rolling average for the hourly interval (. MSU_4HRA = LAST (V_MSU_4HRA). For example, if your recording interval is 15 minutes then the ‘MSU_4HRA’ value reported for 20th hour in TDS will be the value which occurred at 20:45(the last effective 4HRA value for that hour). This is the reason your ‘MSU_4HRA’ value would not match with your SCRT value.

LPAR Name	SMF interval	15 min interval MSU 4HRA	1 Hour interval data in MVSPM_LPAR_H at 01:00:00
A	01:00:00	35
A	01:15:00	35
A	01:30:00	36
A	01:45:00	35	TDS Value : 35(Last Effective 4HRA)
LPAR Name	SMF interval	15 min interval MSU 4HRA	1 Hour interval data in MVSPM_LPAR_H at 03:00:00
A	03:00:00	33
A	03:15:00	33
A	03:30:00	34
A	03:45:00	34	TDS Value : 34(Last Effective 4HRA)
LPAR Name	SMF interval	15 min interval MSU 4HRA	1 Hour interval data in MVSPM_LPAR_H at 20:00:00
A	20:00:00	53
A	20:15:00	53
A	20:30:00	52
A	20:45:00	50	TDS Value : 50(Last Effective 4HRA)

USING MVSPM_SYSTEM_H

MVSPM_SYSTEM_H also contains the ‘MSU_4HRA’ (SMF70LAC) for each LPAR However, the value of MSU_4HRA reported in this table is the average (MSU_4RHA = Avg (SMF70LAC, INPUT_RECORDS) of SMF70LAC SMF interval records. The MSU_4HRA values reported in this table always matches your SCRT report because SCRT uses the mean of SMF interval records to aggregate an hourly record. For example, if your SMF recording interval is 15 minutes then the MSU_4HRA value reported for 20th hour will be the average of SMF interval records (In this case AVG (20:00,20:15,20:30,20:45).

LPAR Name	SMF interval	15 min interval MSU 4HRA	1 Hour interval data in MVSPM_LPAR_H at 01:00:00
A	01:00:00	35
A	01:15:00	35
A	01:30:00	36
A	01:45:00	35	TDS Value : 35.25(Average 4HRA)
LPAR Name	SMF interval	15 min interval MSU 4HRA	1 Hour interval data in MVSPM_LPAR_H at 03:00:00
A	03:00:00	33
A	03:15:00	33
A	03:30:00	34
A	03:45:00	34	TDS Value : 33.5(Average4HRA)
LPAR Name	SMF interval	15 min interval MSU 4HRA	1 Hour interval data in MVSPM_LPAR_H at 20:00:00
A	20:00:00	53
A	20:15:00	53
A	20:30:00	52
A	20:45:00	50	TDS Value : 52(Average 4HRA)

Tivoli Decision Support for Z/OS provides the functionality to track the last effective 4 Hour Rolling Average and Mean 4 Hour Rolling Average. It is very important to understand the context of each of these values while reporting. The ‘MVSPM_SYSTEM_H’ should be used as a baseline while comparing your results with SCRT. However, to keep track of the last effective 4 HRA in an hour ‘MVSPM_LPAR_H’ becomes an ideal choice.

How SCRT Reports the 4 Hour Rolling Average?

The Detail LPAR Data (N5) section of the SCRT report shows the interval (date and hour) during the month for each LPAR on a CPC when the LPAR reached a maximum rolling 4-hour average utilization value (in MSUs). It also shows the interval in which the sum of all the LPARs reached a maximum rolling 4-hour average value. The SMF Recording interval varies from site to site based on the installation needs. The SCRT algorithm calculates 4HRA values at the hourly interval by taking an hourly average of 4HRA values at each of the LPAR SMF intervals. In the below example the SMF recording interval for LPAR A is 15 minutes and the peak reported in SCRT occurred at 20:00, so SCRT here has taken the mean of all the 4 intervals of 20th hour. 

LPAR Name	SMF interval	15 min interval SMF70LAC values	SCRT value reported in N5 section at 20th hour
A	20:00:00	53
A	20:15:00	53
A	20:30:00	52
A	20:45:00	50	Calculated value: AVG(20:00,20:15,20:30,20:45) 52 MSUs