RAID is not a backup solution, it is a hardware failure solution. You will
not be protected against user error. Running a mirror with a delay gives you
a chance to recover accidentally deleted files.
For backups:
dd: Perfect copy. Only works with identical partitions. Slow (copies empty
space). No incremental backup.
cp: Can't delete files.Doesn't handle hard links.
rsync: Keeps all attributes. Handles hard links. Allows incremental backup.
Can delete files.
BTW there are lots of hard links on a Linux box, run
find / -type f \! -links 1
My choice:
rsync --archive --hard-links [ --delete | --backup ] SRC DST
~mark
