Its been well documented for a while that Oracle were not going to allow raw devices in 12….but this still seems brutal.
8.1.12 Desupport for Raw Storage Devices
Starting with Oracle Database 12c, block file storage on raw devices is not supported. You must migrate any data files stored on raw devices to Oracle ASM, a cluster file system, or Network File System (NFS).This also affects the OCR and voting files for Oracle Clusterware. You cannot store the OCR or voting files on raw devices. Oracle Clusterware files must be moved to Oracle ASM before upgrading.
So for all those customers running raw (most typically seen on OS clusters, where clustered file systems were an additional license…) then you’ve got some more upgrades coming your way