Displaying historical data

This section provides information about the historical data feature. Historical data lets you look at system data as it existed an hour ago, yesterday, last week, last month, or last year.

Note

For instructions about how to generate historical performance reports, see BMC AMI Ops Infrastructure.

Overview

Historical data lets you recreate the operating environment as it existed during a previous time frame so that you can compare the current performance with a previous performance. This comparison lets you determine whether your system is working normally or experiencing a problem.

Historical data consists of your data from a specified recent interval and its preceding intervals. Using the TIME command, you can specify intervals from any time frame for which data exists on your system. You can also use certain fields to determine when the data was collected and to hyperlink to a particular time frame.

Data availability

When you need historical data, you must ensure that the data is available in one of the historical data sets that has been allocated.

To determine whether data has been recorded to historical data sets, and to view a list of allocated historical data sets, type DSLIST on the COMMAND line. The DSLIST view is displayed.

Each of the following components are used to collect and display history data:

Linux data servers
z/VM data servers
MainView for Linux — Servers product address space (PAS)
BMC AMI Ops Display

Linux data servers and z/VM data servers

The Background Sampling Mode Interval controls how often the data server requests the collection software for data samples. The Background Sampling Mode Interval (default= 1 minute) is set in the Monitor Rules. For more information about the Background Sampling Mode Interval and Monitor Rules , see Using rules and images.

MainView for Linux — Servers product address space (PAS)

The PAS receives the incoming data samples from the Linux and VM data servers and summarizes the data samples with the records in the current interval data record buffers.

Numeric data is averaged by using the number of samples received for the current interval.

The PAS Interval Recorder has its own interval, which is specified in the BBPARM member MMLTIR00, by using the keyword INTVAL. For more information about how to specify this interval, see Using-manual-customization. At the end of every interval, Interval Recorder writes the current interval record data buffers to one of the VSAM history data sets. These history data sets were allocated during the PAS customization. For more information about the history data sets allocation, see Customizing-after-installation.

The INTVAL value determines when data is written to the history data set, which controls the granularity of the data. Smaller values for Background Mode Sampling Interval and the INTVAL value increase collection overhead, but yield more accurate data. Higher values smooth out the peaks and valleys of the data samples, but they decrease the collection overhead.

BMC AMI Ops display

Historical data views have the following two fields at the end of every row:

Last Sample Time field
Last Sample Date field

These fields are specific to MainView for Linux — Servers. The date and time values are local to the Linux or z/VM system where the data server is running. These values are provided so that you can accurately determine when the data was sampled, because the Linux or z/VM system could be in a time zone different from the PAS or there could be some network delay of the sample data flowing to the PAS could have occurred.

If the INCLUDE DATE and INCLUDE TIME commands have been issued, BMC AMI Ops also displays the following fields:

PAS Interval Date field
PAS Interval Time field

These fields specify when the Interval Recorder interval ended in the PAS. This date and time are local to the system where the PAS is running.

TIME command

You can use the TIME command to specify the intervals of historical data that you want to display. The TIME command lets you display data as it existed at the end of one interval. To see data that spans a greater time frame, use the TIME duration parameter with the date and time parameters.

For detailed information about using the TIME command, the syntax of the command, and examples of different uses of the TIME command, see BMC AMI Ops Infrastructure.