You can use SnapDrive for Windows to manage LUNs not created by SnapDrive by completing these steps to prepare the LUNs for SnapDrive management.
If the LUN was created with ostype set to a different value than you need, you can create a new LUN using SnapDrive, copy the data to it, and delete the original LUN. You can use System Manager or FilerView to check the ostype of the LUN. For more information about ostype, see the Data ONTAP Block Access Management Guide for iSCSI and FC.