title: vagrant vm not starting after adding storage device
body: <p>I want to create vm using vagrant with 2 disks. vm is showing error on gui "FATAL: Could not read from boot medium". It runs fine if created without any disk any disk.
  Here is my Vagrantfile:</p>
  
  <pre><code>VAGRANTFILE_API_VERSION = "2"
  
  Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
      config.vm.define "cn1" do |cn1|
              cn1.vm.box = "trusty"
              cn1.vm.hostname = "cn1"
              cn1.vm.network "private_network", ip: "192.168.100.11"
              cn1.vm.network "private_network", ip: "10.10.10.11"
              cn1.vm.host_name = "controller1"
              cn1.vm.provider :virtualbox do |vb|
                      vb.memory = 500
                      vb.customize ["createhd",  "--filename", "machine1_disk0", "--size", "8192"]
                      vb.customize ["createhd",  "--filename", "machine1_disk1", "--size", "8192"]
                      vb.customize ["storagectl", :id, "--name", "SATA Controller", "--remove"]
                      vb.customize ["storagectl", :id, "--name", "SATA Controller", "--add", "sata"]
                      vb.customize ["storageattach", :id, "--storagectl", "SATA Controller", "--port", "1", "--type", "hdd", "--medium", "machine1_disk0.vdi"]
                      vb.customize ["storageattach", :id, "--storagectl", "SATA Controller", "--port", "2", "--type", "hdd", "--medium", "machine1_disk1.vdi"]
                      vb.gui = true
              end
      end
  end
  </code></pre>