Viewing past data

You can recall and view statistics, thread activity, and system parameters data previously collected by the data collector. The data is gathered at installation-defined intervals.

You can view past data by issuing the HISTORY command or pressing F6 (History) in any panel that can display past data.

When viewing past data, the word HISTORY is displayed on the line following the heading of the current panel.
Figure 1. Thread Detail panel showing history active
 DGOMTPSM 11:57                   Thread Detail              PMO1DLOC DSN1 V10

                                  GROUP001 MEMBER01 HISTORY 05/30/08 11:45:00
For details, place any character next to heading, then press Enter.
The date and time following the word HISTORY indicate when the data being displayed was collected.
Note: You can view past data only if the data collector is installed at your site.
Your installation can choose to collect data at the following levels:
  • Thread Summary
  • Thread Detail
  • Thread Detail with locking information
  • Thread Detail with SQL statement
  • Thread Detail with locking information and SQL statement
  • Statistics
  • System Parameters

Historical data is kept in either a VSAM data set or data space. The data is gathered by the data collector. When the data set or data space is full, the data is written to the beginning again, writing over the earliest data gathered.

The availability of the data is limited by the collection rate, the size of the data space or data set used, the amount of historical data to be maintained, and the thread history qualification definitions (all of these are defined in the data collector startup parameters).

The data collector parameters can also be modified by the administrator user.

The syntax of the HISTORY command is:
Figure 2. Syntax of the HISTORY command
Read syntax diagramSkip visual syntax diagramHISTORYOFFBACKFORWARDdatehh:mm:ss
The HISTORY command accepts the following parameters:
Returns the display to the current time.
Displays data for the previous interval. If no more data is available, data from the earliest available interval is displayed.
Displays information for the next available interval. If no data is available, data from the current time is displayed and processing continues as if HISTORY is OFF.
The date of the required information. If no date is specified, today’s date is assumed.
The time of the required information. If no time is specified, the default is the time of the earliest available history record for the specified date. The seconds do not need to be specified.
Note: HISTORY can be truncated to a minimum of HIS.

If no data is available for the specified date and time, the next available record is displayed.

When a panel is refreshed while viewing past data, the panel is updated with data from the next stored record, just as if you had entered HISTORY FORWARD on the command line.

If no parameters are specified, the History window is displayed.
Figure 3. History window
 DGOMHWHY                      History

                      05/09/08  14:03

 Date . . . . . . . . . 03/16/08
 Time . . . . . . . . . 14:03:24

 F1=Help    F2=Split   F9=Swap

The current system date and time are the defaults for the History window.

Note: When monitoring with HISTORY OFF, it is possible to view data that cannot be viewed by using the HISTORY command. This occurs when the “current moment” does not coincide with the history collection interval. For example, when the history interval is 10 minutes in length and data is collected at 8:30 and 8:40, the data retrieved at 8:32 from DB2® is not subsequently retrievable using the HISTORY command.

A sample JCL is provided in library RKO2SAMP(DGOMMJCL) that can be used to unload history VSAM data sets created by the data collector. After unloading, you can use the data as input to the batch Record trace function for problem determination. The sample JCL might need to be modified.