SMF 100-202 Buffer Pool

Introduction

DB2 statistics will be collected from SMF type 100. In this type of record, it doesn’t really matter the SMF subtype of the SMF record because DB2 uses another specification type to distinguish different SMF specializations.

In DB2 there is an identification named IFCID (Instrumentation Facility Component Identifier) each one with different data and purpose.

The statistics trace reports information about how much the Db2 system services and database services are used.

You can use the information that the statistics trace provides to plan Db2 capacity or to tune the entire set of active Db2 programs.

If you specify YES for the SMF STATISTICS entry in panel DSNTIPN, the statistics trace uses classes 1, 3, 4, 5, and 6 as the defaults. If the statistics trace is started using the START TRACE command, the statistics trace uses class 1 as the default.

The following table describes the Db2 statistics trace classes.

If you specify YES for the SMFSTAT subsystem parameter, the statistics trace starts automatically when you start Db2, and sends the default classes (classes 1, 3, 4, 5, and 6) statistics data to SMF. SMF records statistics data in both SMF type 100 and 102 records. IFCIDs 0001, 0002, 0202, 0225, 0230, and 0369 are of SMF type 100. All other IFCIDs in statistics trace classes are of SMF type 102.

When you specify CLASS(7) or IFCID(365) in a START TRACE or MODIFY TRACE command, Db2 writes IFCID 0365 records. These records are written to the specified destination of the statistics trace for remote locations that communicate with the subsystem. Statistics are generated only for those locations that have activity since the record was generated. The location statistics are written each time that the STATIME interval elapses. Statistics can be written for as many as 95 remote locations.

Db2 also writes statistics about all DRDA locations with the other default statistics trace data to a single SMF location named DRDA REMOTE LOCS, whenever other default statistics are written.

Statistics trace classesThe following table shows the IFCIDs that are activated for each statistics trace class.Table 1. Classes for Db2 statistics traceClassDescription of classActivated IFCIDs1Information about system services, database statistics, statistics for the database services address space (ssnmDBM1), and information about the system parameters that were in effect when the trace was started. This default class is also activated when you omit the CLASS keyword from the START TRACE command when you start the statistics trace.0001, 0002, 0105, 0106, 0202, 02252Installation-defined statistics record01523Deadlock, lock escalation, group buffer pool, data set extension information, and indications of long-running uncommitted reads, and active log space shortages.0172, 0196, 0250, 0258, 0261, 0262, 0313, 0330, 03374Db2 exceptional conditions.0173, 0191-0195, 0203-0210, 0235, 0236, 0238, 0267, 02685Db2 data sharing statistics record.02306Storage statistics for the Db2 subsystem.02257DRDA location statistics.03658Data set I/O statistics.01999Aggregated CPU and wait time statistics by connection type.036910 - 29Reserved. 30 - 32Available for local use.

Intervals for collecting Db2 statistics trace records
Db2 collects statistics trace records for the following IFCIDs at the interval specified by the STATIME and SYNCVAL subsystem parameters. For more information, see STATISTICS TIME field (STATIME subsystem parameter) and

STATISTICS SYNC field (SYNCVAL subsystem parameter)

0105 (Db2 performance trace)
0106 (system parameters)
0199 (data set statistics)
0365 (remote location statistics)
0402 (monitor profile warnings or exceptions)
Db2 collects statistics trace records for other IFCIDs at fixed one-minute intervals.

CSV I202 for SMF 100 IFCID 202, including PROD section and Buffer Manager Dynamic Pool Atributes stats.

Fields

Stored in dbsi202