Journal file is actually a system file that stores all the vital information present in Mac OS X. It protects the data from getting lost due to any unexpected power failure. So if your Mac system shut down abruptly, do not get worried, as on start up of your system again, this journal file will restore the volume back to its previous working state. HFS, HFS+ and most of the files systems supports files system journaling making it less prone to errors.
But some serious consequences can make these journal files corrupted. In such circumstances your Mac volume becomes fully inaccessible resulting in huge data loss. Loss of your crucial data can put you in some risky situations thus it becomes very important to retrieve data from your inaccessible Mac volumes. You can also use Mac Data Recovery Tool to get back your lost Mac data.
