Disk formatting: This is necessary when converting the file system, but the operation erases everything on the external hard drive. For this situation, first try data recovery software ...

When booted, a recovery ... or hard disk recovery to the computer's original state is to periodically back up the entire primary hard drive onto a second internal hard drive or to an external ...

Luckily there are apps that can recover ... software and file system support. The software still supports the HFS+ format, FireVault 1 and 2, Core Storage for Fusion dries, RAID configurations ...