To configure the properties for the Continuous Historian subsystem, right-click the Continuous Historian subsystem under the workstation, and select Properties from the context menu. In the Continuous Historian Properties dialog, click the Advanced tab to set the following parameters for the DeltaV Continuous Historian:
If you are running the Advanced Continuous Historian or OSIsoft PI Server on the selected workstation, these parameters are configured in the PI System Management Tools (PI SMT).
On the Advanced tab, the Historian Storage options determine the automatic actions used to control the amount of disk space used for Primary storage. The maximum historical database size establishes a target for the maximum amount of disk storage used in the Primary storage area for the combined active and current historical data sets. Extended historical data sets do not count against the target. The configurable range is 100 MB to 10,000 MB, with a default of 600 MB.
When the Primary storage used for active and current historical data sets goes above the target size, the historian will delete the oldest current historical data set or sets to reduce storage to within the target. If automatic historical data exporting is enabled, an attempt to export the historical data set will be made before it is deleted.
In addition to specifying a target size for the Primary storage, you can specify a maximum historian time span in days, up to a maximum of 9,999 days, that current historical data sets will remain in Primary storage. Once the newest data in a current historical data set is older than the expiration time span, the historian is authorized to automatically remove the data set. If the data set expires while in Primary storage, automatic historical data exporting, if configured, is first attempted before the data set is discarded.
Rules exist to determine when an active historical data set rolls over to become a current historical data set. A new active historical data set is created when the rollover occurs.
This property determines if historical data should be exported automatically before it is deleted from online storage. If automatic exporting is enabled, specify the path to a directory available to that workstation where exported historical data should be stored. If the maximum historian storage size is exceeded, historical data set deletion will still be performed even if the historical data sets cannot be stored in the specified directory. It is recommended that the export directory be on the same workstation where the Continuous Historian subsystem is enabled, but outside of the DeltaV system directory. Using mapped drives is not recommended because a mapped drive may not always be connected when the historian is trying to export data.