Report history is a collection of report snapshots that you create over time. You can create report history on demand, or schedule how often a snapshot is created and added to report history.
Report history is stored in the report server database. If report snapshots contain a large amount of data, you might consider limiting report history to minimize the affect of snapshot retention on database size.
To configure report history for a report server
In Report Manager, click Site Settings on the global toolbar.
Select Keep an unlimited number of snapshots in report history if you want to keep all report history indefinitely. Otherwise, select Limit the copies of report history to specify the maximum number of snapshots that can be kept for any given report.
To configure report history for a specific report
In Report Manager, navigate to the report for which you want to configure history, and then click the report to open it.
Click the Properties tab.
Click the History tab.
Select the options for your report and click Apply. For details about each option, see Snapshot Options Properties Page (Report Manager).