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.