Monitors for a large change in value of database available space over a set number of sample periods. A rapid large change in value could indicate a problem.
An unhealthy state is caused by a large change in available space over a set number of sample periods. This can be caused by:
A large auto growth setting for a file set to auto grow.
A fast growing file that consumed a large amount of available space within a short period.
A foreign object or file consumed a large amount of available space hosted on the same disk as this file
Use the following link to view the performance data: Database Performance Data
This monitor aggregates the space available for each file within a file group depending on each file’s configuration:
No Auto Grow
For a file that has no auto grow, available space would be the difference between the initial size for a file and the used space.
Auto Grow Enabled
In addition to the difference between the file size and the used space, the available space for files with auto grow enabled would be the minimum of either the difference between the max size and the file size and the free space left on disk.
The available space calculations also take into account that the file can also fail to grow if the growth amount of the file is greater than the amount left on disk and that the file cannot grow if the difference between the max size and the current file size is less than the growth amount. In these situations, available free space left on disk is not included as part of the available space because we cannot grow any longer.
This issue may be resolved by either:
Decreasing the growth amount for files with auto grow
Modifying the thresholds for this monitor to suit the workload
Alternatively if space percentage change is not a concern for the database:
Disable this monitor for this specific database or all databases