diff --git a/plugins/kernel_v2/config/disk.rb b/plugins/kernel_v2/config/disk.rb
index f903cd366..7c0386cdf 100644
--- a/plugins/kernel_v2/config/disk.rb
+++ b/plugins/kernel_v2/config/disk.rb
@@ -8,6 +8,8 @@ module VagrantPlugins
       # Config class for a given Disk
       #-------------------------------------------------------------------
 
+      DEFAULT_DISK_TYPES = [:disk, :dvd, :floppy].freeze
+
       # Note: This value is for internal use only
       #
       # @return [String]
@@ -29,17 +31,20 @@ module VagrantPlugins
       # @return [String]
       attr_accessor :name
 
-      # Type of disk to create
+      # Type of disk to create. Defaults to `:disk`
       #
       # @return [Symbol]
       attr_accessor :type
 
       # Size of disk to create
       #
+      # TODO: Should we have shortcuts for GB???
+      #
       # @return [Integer]
       attr_accessor :size
 
-      # Determines if this disk is the _main_ disk, or an attachment. Defaults to true
+      # Determines if this disk is the _main_ disk, or an attachment.
+      # Defaults to true.
       #
       # @return [Boolean]
       attr_accessor :primary
@@ -60,8 +65,9 @@ module VagrantPlugins
       def initialize(type)
         @logger = Log4r::Logger.new("vagrant::config::vm::trigger::config")
 
+        @type = type
+
         @name = UNSET_VALUE
-        @type = UNSET_VALUE
         @provider_type = UNSET_VALUE
         @size = UNSET_VALUE
         @primary = UNSET_VALUE
@@ -102,11 +108,13 @@ module VagrantPlugins
       def finalize!
         # Ensure all config options are set to nil or default value if untouched
         # by user
-        @name = nil if @name == UNSET_VALUE
-        @type = nil if @type == UNSET_VALUE
+        @type = :disk if @type == UNSET_VALUE
         @size = nil if @size == UNSET_VALUE
         @primary = true if @primary == UNSET_VALUE
 
+        # generate name instead of nil if unset_value
+        @name = nil if @name == UNSET_VALUE
+
         @config = nil if @config == UNSET_VALUE
       end
 
@@ -116,6 +124,15 @@ module VagrantPlugins
 
         # validate type with list of known disk types
 
+        if !DEFAULT_DISK_TYPES.include?(@type)
+          errors << "Disk type '#{@type}' is not a valid type. Please pick one of the following supported disk types: #{DEFAULT_DISK_TYPES.join(', ')}"
+        end
+
+        # TODO: Convert a string to int here?
+        if !@size.is_a?(Integer)
+          errors << "Config option size for disk is not an integer"
+        end
+
         errors
       end
 
diff --git a/plugins/kernel_v2/config/vm.rb b/plugins/kernel_v2/config/vm.rb
index 5734cebae..69aab52f2 100644
--- a/plugins/kernel_v2/config/vm.rb
+++ b/plugins/kernel_v2/config/vm.rb
@@ -580,7 +580,6 @@ module VagrantPlugins
           end
         end
 
-        # TODO: This might need to be more complicated
         @__disks.each do |d|
           d.finalize!
         end
@@ -786,6 +785,17 @@ module VagrantPlugins
           end
         end
 
+        # Validate disks
+        # Check if there is more than one primrary disk defined and throw an error
+        if @__disks.select { |d| d.primary && d.type == :disk }.size > 1
+          errors << "There is more than one disk defined for guest '#{machine.name}'. Please pick a `primary` disk."
+        end
+
+        @__disks.each do |d|
+          error = d.validate(machine)
+          errors.concat error if !error.empty?
+        end
+
         # We're done with VM level errors so prepare the section
         errors = { "vm" => errors }