When installing a new clustered instance, you will probably want to assign multiple disk drives to a SQL instance. After you define all clustered resources and install instance, instance will only see the disk drive where you put your default data files. For any additional disk drives, you have to manually apply the solution below.
In a SQL Cluster Administration, open the "SQL Server" resource, click on "Dependencies" and add the disk resource you want to be able to use.
"SQL cluster" "Select the folder:" "can't see disk"