Overview of PDS V1

The persistent data store is used for writing and retrieving historical data. The data written to the persistent data store is organized by tables (attribute groups), groups, and data sets. Each table is assigned to a group. Multiple tables can be assigned to each group, and each group can have one or more data sets assigned to it. By default, six data sets are assigned to a group.

Important: The content in this section was created for and applies to the original persistent data store, referred to as PDS V1. A new PDS version (referred to as PDS V2) now exists. PDS V1 will eventually be deprecated.

One of the data sets in each collection group is kept empty so that it can be quickly switched to if the active data set fills up. After this switch is made, the persistent data store looks to see if there are any empty data sets in the group. If not, the automatic maintenance process empties the data set with the oldest data.

During configuration, you allocate space for the data sets and specify what is to be done with historical data that is sitting in a data set that is being emptied. The default is to delete the data. Alternatively, you can configure maintenance to back up the data to tape or DASD, export the data to an external program for processing, or extract the data and write it in a viewable format.

Note that if the Tivoli Data Warehouse is used, especially with a 1-hour warehousing interval, there is little or no advantage to invoking the BACKUP, EXPORT, or EXTRACT functions for data collected by an OMEGAMON monitoring agent. These functions are more relevant if warehousing is not enabled, or if you are maintaining historical data for OMEGAMON agents whose data is not displayed by the Tivoli Enterprise Portal.

No historical data collection takes place until collection is configured and started through the OMEGAMON enhanced 3270 user interface or the History Collection Configuration window of the Tivoli Enterprise Portal. In the window, you specify the attribute groups for which you want data to be collected, the interval for data collection, and the location where you want the collected data to be stored (at the monitoring server or at the agent). In the Tivoli Enterprise Portal, you can also specify whether you want to store the data in the Tivoli® Data Warehouse so it will be available for long-term history data reporting.