-a, --archive archive mode; equals -rlptgoD (no -H,-A,-X)

-r, --recursive recurse into directories
-l, --links copy symlinks as symlinks
-p, --perms preserve permissions
-t, --times preserve modification times
-g, --group preserve group
-o, --owner preserve owner (super-user only)
-D same as --devices --specials

--devices preserve device files (super-user only)
--specials preserve special files