Get booted back into ALARM however you like, then install this package to see what happens:
$this->bbcode_second_pass_code('', 'pacman -U http://archlinuxarm.org/builder/testing/uboot-goflexhome-2014.04-1-arm.pkg.tar.xz')
This includes a change that supposedly enables addressing >2TB. If this works for you, it will be merged into the repo packages.