The procedure principally involves finding the data on the raw partition
device and making it visible again to the operating system. There are
basically two ways of doing this: one is to modify the existing file system such
that the deleted inodes have their `deleted' flag removed, and hope that the
data just magically falls back into place. The other method, which is safer
but slower, is to work out where the data lies in the partition and write it
out into a new file on another file system.