1. Go to Configure | Scheduling option, from top of screen in Spotlight.
2. Click the drop-down menu and select the SQL Server to report on.
3. Ensure the check box "Collect and Store Repository Data" is checked.
4. Locate the collection named "Virtual File Statistics". Check the "Keep for" column for this collection.
5. If it's less then the amount of desired time, then double-click to open and uncheck "Factory Settings" if checked.
6. Ensure Store data is checked and change the "Keep data for x Days" to desired number of days and click OK.
Do the same for the following collections in the same window:
- SQL CPU Percent,
- SQL Analysis
- SQL Statistics
- Tempdb Performance Counters
- Buffer Manager