The Packaged CCE Logger retention settings and database size are configured to ensure sufficient database space for the data. In the unlikely event that the Logger's Central Database becomes full or reaches a configured threshold size, Packaged CCE frees up database space by running an emergency purge on historical database tables.
The emergency purge goes through each historical table in a predefined order one at a time and purges one hour's worth of data from the table, looping through the tables if necessary. As data is purged from each historical table, a check is made to verify if the free space is more than the minimum threshold value. Once adequate space has been recovered, the emergency purge procedure stops.
If your deployment does not include an external HDS and uses only the Logger for data storage, emergency purge results in a permanent loss of data. If your deployment does include an external HDS, permanent loss of historical data can occur if the emergency purge removes historical data that has not yet made it to an external HDS and been replicated to the peer Logger.