302 DB2 Performance Expert for Multiplatforms V2.2
Performance Warehouse - Expert
The Performance Warehouse is a large component of Performance Expert. It
is split into three areas:
Processes: Which can be scheduled.
Rules of Thumb: Which can be tailored or new ones added.
Warehouse queries: 25 predefined queries and option to create your own.
The areas of Performance Warehouse that specifically relate to buffer pools is
covered in 5.2.4, “Performance Warehouse for buffer pool analysis” on
page 312.
Buffer Pool Analysis
This is the menu item dedicated to investigating buffer pools. This function is
split into two main areas, which are generated simultaneously each time a
buffer pool report is created: Text Reports and Interactive Reports. The report
generation and content of these reports are described in 5.2.1, “Generating
Buffer Pool Analysis reports” on page 302.
5.2.1 Generating Buffer Pool Analysis reports
In DB2 Performance Expert, all buffer pool information is derived from DB2
snapshots. The snapshots are taken periodically as set in the Recording interval
field, in the Performance Expert Server Properties panel under the History tab. In
these examples, the snapshots are taken every 60 seconds. The information
used to populate the Buffer Pool Analysis reports is stored in the Performance
Warehouse. This data is summarized based on the Granularity for summarizing
the history data field in the Performance Expert Server Properties panel under
the Performance Warehouse tab in the client (see Figure 5-37 on page 303).
Chapter 5. Features and functions - long-term monitoring 303
Figure 5-37 Performance Expert Server Properties - PWH
For example, if the granularity is set to one, the history snapshots that are taken
every 60 seconds will be summarized over 15-minute periods, resulting in four
rows per hour in the Performance Warehouse tables. It is this summarization
data that is used to populate the buffer pool reports.
304 DB2 Performance Expert for Multiplatforms V2.2
The first time you access the Buffer Pool Analysis screen, no databases or
reports are displayed, as shown in Figure 5-38.
Figure 5-38 New BPA screen
The next step is to generate reports for the databases and time periods in which
you are interested. On the Buffer Pool Analysis menu bar, select File
Generate New Report or use the toolbar button ( ).
The Report Generation dialog box is displayed (see Figure 5-39 on page 305).
From here you select the database on which you are reporting from the drop
down list, and enter the start and end times for the reporting period.
Chapter 5. Features and functions - long-term monitoring 305
Figure 5-39 Report Generation parameter dialog box
The End time defaults to the last time stamp of available data in PWH, and the
Start time defaults to the End time less the previously monitored period. But be
aware that the period you specify to report on may not exactly match the period
for which snapshots were taken.
In the example shown, we are reporting on a non-partitioned database, namely
PEDEMO. The Snapshot Types field determines whether we include tables in the
report, or just buffer pools and tablespaces.
Click OK to continue to the next pop-up screen, which displays the progress
generating the Text Reports and Interactive Reports (seen in Figure 5-40 on
page 306).
Note: Although the Report Generation pop-up allows you to specify very
specific start and end times, the reports will only include information from the
summarized history data in the Performance Warehouse, at best, every 15
minutes.
Therefore, it is prudent to only generate reports that are coincident with the
summarization of your warehouse reporting.
Note: The dates in the dialog box are displayed in the format of the machine
where the PE Client is installed.
306 DB2 Performance Expert for Multiplatforms V2.2
Figure 5-40 Buffer Pool Analysis Report Generation
After you have generated several reports, the Buffer Pool Analysis screen will
look similar to Figure 5-41 on page 307. The reports are grouped into Text
Reports or Interactive Reports, and further grouped by database.

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