Spotlight calculates the number of times the file group could grow before hitting the defined limits.
This alarm is ignored if Auto Grow=No for all files in the file group. The growths remaining is set to null.
While this alarm is current
Open the SQL Server | Databases Drilldown | Data Files page. In the Data Files grid, check for files with Auto Grow=Yes. Files in danger of filling will have a low Free Pct figure.
To resolve this problem
Free up disk space on the disk that the file resides on.
Spotlight alarm configuration
In Spotlight Enterprise from the Spotlight Client you can configure this alarm to ignore certain values.