This option allows you to enable or disable the journaling of the disk.
If journaling is turned on for a disk, Mac 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, Mac OS X uses the journal to restore the hard disk to the last acceptable state before it was stopped.
Note: If journaling is disabled, it's not possible to verify the structure of System Files on the startup volume.