If your system has changed to systemd you should be able to control the global setup with the
localectl command. Check the current settings with
$ localectl status
List the possible keyboard variants, including dvorak, with
$ localectl list-x11-keymap-variants
Set the new global keyboard and locale with
$ localectl set-x11-keymap ...
where you need to give, in order, the layout, model, and variant (dvorak). Use the layout and model got from the status output. See
set-x11-keymap option is
supposed to change the console tty keymap automatically as well. However, if it doesn't do a good enough job, you can explicitly set the console tty keymap eg with
$ localectl --no-convert set-keymap us-dvorak
--no-convert to not disturb the X11 map).
localectl list-keymaps to see what dvorak names are possible.