Long-term historical data is kept in the Central Repository.
It can be exported to this database on an interval (i.e. every 30 minutes). Data can be kept for months or years, and reduction facilities are provided.
Central Repository
The Central Repository is a database (i.e. ASE, SQL Server) that stores long-term historical data, i.e. for long-term trend analysis.
Reports
Web Reporting provides long-term history reports from the web client.