How can a journal added, non-destructively, to the ext2 file-system on /dev/dg/lv05?
Please enter the command with all parameter(s):

Answer: tune2fs -j

Explanation:
/dev/dg/lv05

From the man pages
tune2fs – adjust tunable filesystem parameters on second extended filesystems
tune2fs [ -j ] [ -J journal-options ] device
-j Add an ext3 journal to the filesystem. If the -J option is not specified, the default journal
parameters will be used to create an appropriately sized journal (given the size of the filesystem)
stored within the filesystem.
Note that you must be using a kernel which has ext3 support in order to actually make use of the
journal.