When you move a volume to FabricPool, you have the option to specify or change the tiering policy for the volume with the move.
The following example moves a volume named "myvol2" of the "vs1" SVM to the "dest_FabricPool" FabricPool-enabled aggregate. The volume is explicitly set to use the none tiering policy:
cluster1::> volume move start -vserver vs1 -volume myvol2 -destination-aggregate dest_FabricPool -tiering-policy none