Backup Files Must Be on Separate Devices from the Database Files
Applies To: SQL Server 2016
This rule checks whether database files are on devices separate from the backup files. If database files and backup files are on the same device and the device fails, the database and backups will be unavailable. Also, putting the database and backup files on the separate devices optimizes the I/O performance for both the production use of the database and the writing of backups.
We strongly recommend that you put the database and backups on separate backup devices.