The File Groups Growth chart shows the amount by which each file group is growing over time.
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The file groups displayed can be restricted by clicking on the database(s) of interest in the Databases grid at the top of the drilldown. They can then be further restricted by clicking on just the file groups of interest in the File Groups grid in the middle of the drilldown. Hold down the Shift key to select multiple file groups, or the CTRL key to select individual file groups.