# File lib/fog/ecloud/models/compute/server.rb, line 111
        def add_disk(size)
          if @disk_change == :deleted
            raise RuntimeError, "Can't add a disk w/o saving changes or reloading"
          else
            @disk_change = :added
            load_unless_loaded!
            virtual_hardware[:Item] << { :ResourceType => '17',
                                         :AddressOnParent => (disk_mess.map { |dm| dm[:AddressOnParent] }.sort.last.to_i + 1).to_s,
                                         :VirtualQuantity => size.to_s }
          end
          true
        end