SQL Server Free Disk Space Alert using PowerShell

Alerting on free disk space for your SQL Server instance is not a base alert within DPA. This is because the information is not readily available from within the database instance via a query. However, using xp_cmdshell and a PowerShell command, we can add a custom alert to DPA to handle this. Note: the xp_cmdshell option is disabled by default on SQL Server instances. For this alert to work properly, xp_cmdshell must be enabled.

When creating the alert in DPA, create a Custom Alert of type "Custom SQL Alert - Multiple Numeric Return".

The PowerShell script uses the Win32_Volume object which supports mount points as well as standard drives.