Short-term history and long-term history
While the short-term history is generated from the persistent data store (PDS), the long-term history is generated from IBM® Tivoli® Data Warehouse.
You can write the short-term data from PDS datasets to Tivoli Data Warehouse for long-term retention. Use the History Configuration dialog boxes from within the Tivoli Enterprise Portal to specify the time interval, such as hourly or daily at which short-term data is written to the warehouse. You can then retrieve the long-term historical data for display with the portal.
When a portal display is generated, data comes from the sources that are listed in the following table:
| Source of data | Type of data | Time span of the data |
|---|---|---|
| Persistent data store | Short-term history | 24 hours or less |
| Tivoli Data Warehouse | Long-term history | Over 24 hours |
For some tables, collection of data in Tivoli Data Warehouse is not available. In these cases, the portal can display data from the persistent data store only.
When you allocate space for persistent data stores, keep sufficient space for 24 hours of data. When the option for collection of data in Tivoli Data Warehouse is not available, you can allocate extra space to enable the persistent data store to collect data for a longer period of time, for example, 48 hours. If you set the Time-Span tool in a portal workspace to display data for the last 48 hours from one of these tables, you see 48 hours of data, if you have allocated sufficient storage space in the persistent data store.