You can use this option to turn the journaling of the disk on or off.
If journaling is turned on for a disk, OS X maintains a permanent record of changes made to files on the disk. If your computer stops because of a power failure or some other issue, OS X uses the journal to restore the hard disk to the last acceptable state before it was stopped.
If journaling is turned off, it's not possible to verify the structure of the system files on the startup volume.