Do not mount file systems on a volume's underlying slice. If a slice is used for a volume of any kind, you must not mount that slice as a file system. If possible, unmount any physical device that you intend to use as a volume before you activate it. For example, if you create a transactional volume for a UFS, in the /etc/vfstab file, you would specify the transactional volume name as the device to mount and fsck.