Your Active/Active scenario will not work. There is an inherent restriction with SQL Server that means a given SQL service must have exclusive access to the database file.

If somehow you get past this and get multiple SQL instances to share the same disk in read/write mode you will corrupt the databases. When SQL instance A reads a page from disk to its buffer, it assumes it has 100% control over the page. If SQL instance B replaces the page on disk this is not known to SQL instance A. When SQL instance A writes the page to disk you will destroy the updates made by SQL instance B.

If you really need multiple database instances able to update the same database file, then you need to look at DB2. In DB2 there is instance to instance communication to let all instances know which instance is updating a given database page, so that updates from multiple instances do not get lost.