IDB2 Secondary Extents allocation for History file

Products

• SYSVIEW Performance Management Option for DB2 for z/OS
• Database Management for DB2 for z/OS - Performance Suite
• Database Management for DB2 for z/OS - SQL Performance Suite
• Insight Performance Monitor for DB2 UDB for z/OS

Issue/Introduction

Should secondary extents be  allocated for IDB2 History files based on the following comments of the IDB2 Post-install job or not?

HSTSTATS  - CHANGE THE PRIMARY/SECONDARY ALLOCATION AS NEEDED.
HSTACCTG    YOU MAY SPECIFY THE EXTENDED ALLOCATION ATTRIBUTE.
                REFER TO THE CA SYSVIEW FOR DB2 SYSTEM REFERENCE GUIDE
                FOR ESTIMATING SPACE CALCULATIONS AND ALLOCATION
                CONSIDERATIONS. BY DEFAULT WHEN THE DATASET IS
                INITIALIZED, THE INITIALIZATION ROUTINE WILL KEEP
                EXTENDING THE DATA SET UNTIL SPACE ALLOCATION FAILS.
                IF YOU NEED TO SPECIFY SECONDARY ALLOCATION FOR
                SECONDARY EXTENTS, THEN YOU SHOULD USE THE IDB2UIFI
                UTILITY TO INITIALIZE THE FILE. THE IDB2UIFI UTILITY
                ALLOWS YOU TO SPECIFY THE MAXIMUM NUMBER OF CYLINDERS
                TO USE FOR THE DATASETS VIA THE MAXCYLSTAT AND
                MAXCYLACCT PARAMETERS.  IF YOU ARE ALLOCATING A
                LARGE FILE (THOUSANDS OF CYLINDERS), WE RECOMMEND
                USING THE IDB2UIFI UTILITY TO INITIALIZE THE FILES.
                OTHERWISE THE INITIALIZATION WILL TAKE PLACE WHEN
                THE FILES ARE FIRST OPENED BY THE DATA COLLECTOR.
                THIS PROCESS CAN TAKE MANY MINUTES TO COMPLETE,
                DEPENDING ON THE SIZE OF THE FILES.

Environment

Release : 20.0

Component : CA Insight Database Performance Monitor for DB for z/OS

Resolution

We recommend not defining history files with a secondary extents specification. When the history file is initialized, CA SYSVIEW for DB2 initializes the entire file, which causes the data set to extend into as many extents as possible. Use secondary extents only if you cannot allocate enough space in a primary allocation.