Capacity licensing and histories

Histories that exceed the globalCapacity limits manifest in different ways. If the number of histories in the station is greater than the globalCapacity limit, the resource counter in the station prevents more histories from being created.

In the default History Ext Manager view on the HistoryService, you see a table of all history extensions along with the state of each (enabled, disabled, fault). Included is a total count of all history extensions. However, there is no easy, intuitive way to get a count of those in a particular state or set of states. An extension in a fault state with a Fault Cause of Exceeded history limit indicates a related problem. Simply disabling such an extension does not fix the issue. You must delete the history in the history database, which cannot be done from the HistoryService.

You delete histories from the Database Maintenance view of the History space; but note there are no counts available there. If you delete one or more histories to reduce history count, you must wait until the periodic recount (approximately every 10 minutes) calculates the reduced count. However, you cannot delete the history extension that created the history from there. So it is likely that the history is going to be recreated in the future, unless you delete or modify the history extension that created the history database table.

In addition to history extensions in the same station, other items can create histories, including:

  • History imports in the same station

  • History exports in another station

  • AuditHistory service

  • LogHistory service

These activities add to the count. This is the reason why a station quickly exceeds its history limit.