Journal magic is bad error message is what you get when you try to mount a corrupted drive on Mac. Actually this error is seen at the terminal when you try to fix the drive corruption by using the fsck command in the terminal. The drive corruption can be caused due to many reasons some of them are so severe that the corruption can not be fixed using the disk utility or the fsck command and journal magic is bad error message shows up. May be the drive was wrongly formatted, there was any error while partitioning, file system has been damaged, virus infection etc. Now the only option to remove the corruption is to format the drive. Now you will be worried about the lost data after the journal magic is bad error is dealt with. You can get back the data if you have the backup ready with you. You can either use the time machine backup facility or your personal one. When you are unable to find the backup you can use the Mac data recovery software to restore all the data. You can now easily fix the error journal magic is bad and use the software for recovering files.