Data ONTAP classifies disks based on performance vs capacity and does not allow mixing. When attempting to add an FSAS disk to an aggregate made of SAS disk drives, the following error is displayed Re...Data ONTAP classifies disks based on performance vs capacity and does not allow mixing. When attempting to add an FSAS disk to an aggregate made of SAS disk drives, the following error is displayed Reason: Disk type does not match type of disks in the aggregate. For more information on how Data ONTAP selects disks for aggregate creation, see KB: How does Data ONTAP select spares for aggregate creation, aggregate addition, and failed disk replacement?