diff --git a/lib/vagrant/util/numeric.rb b/lib/vagrant/util/numeric.rb
index 31cdd75d5..f65d8512d 100644
--- a/lib/vagrant/util/numeric.rb
+++ b/lib/vagrant/util/numeric.rb
@@ -57,6 +57,11 @@ module Vagrant
           (bytes / MEGABYTE).round(2)
         end
 
+        # @param [Integer] bytes
+        # @return [Integer] bytes - rounded up to nearest 512
+        def round_to_512(bytes)
+        end
+
         # @private
         # Reset the cached values for platform. This is not considered a public
         # API and should only be used for testing.
diff --git a/plugins/providers/virtualbox/cap/configure_disks.rb b/plugins/providers/virtualbox/cap/configure_disks.rb
index 102a51159..f0e899a94 100644
--- a/plugins/providers/virtualbox/cap/configure_disks.rb
+++ b/plugins/providers/virtualbox/cap/configure_disks.rb
@@ -1,30 +1,104 @@
+require "log4r"
 require "vagrant/util/numeric"
 
 module VagrantPlugins
   module ProviderVirtualBox
     module Cap
       module ConfigureDisks
+        LOGGER = Log4r::Logger.new("vagrant::plugins::virtualbox::configure_disks")
+
         # @param [Vagrant::Machine] machine
         # @param [VagrantPlugins::Kernel_V2::VagrantConfigDisk] defined_disks
         def self.configure_disks(machine, defined_disks)
           return if defined_disks.empty?
 
           current_disks = machine.provider.driver.list_hdds
-          # Compare current disks to config, and if there's a delta, adjust accordingly
-          #
-          # Compare by name if possible
+          require 'pry'
+          binding.pry
+
           defined_disks.each do |disk|
             if disk.type == :disk
+              handle_configure_disk(machine, disk, current_disks)
+            elsif disk.type == :floppy
+              # TODO: Write me
+            elsif disk.type == :dvd
+              # TODO: Write me
             end
           end
         end
 
         protected
 
+        # Handles all disk configs of type `:disk`
+        def self.handle_configure_disk(machine, disk, all_disks)
+          # Grab the existing configured disk, if it exists
+          current_disk = nil
+          if disk.primary
+            current_disk = all_disks.first
+          else
+            current_disk = all_disks.select { |d| d["Disk Name"] == disk.name}.first
+          end
+
+          if !current_disk
+            machine.ui.warn("Disk '#{disk.name}' not found in guest. Creating and attaching disk to guest...")
+            # create new disk and attach
+            create_disk(machine, disk)
+          elsif !compare_disk_state(disk, current_disk)
+            machine.ui.warn("Disk '#{disk.name}' needs to be resized. Attempting to resize disk...", prefix: true)
+            resize_disk(machine, disk, current_disk)
+          else
+            # log no need to reconfigure disk, already in desired state
+            LOGGER.info("No further configuration required for disk '#{disk.name}'.")
+          end
+        end
+
+        # Check to see if current disk is configured based on defined_disks
+        #
+        # @param [Kernel_V2::VagrantConfigDisk] disk_config
+        # @param [Hash] defined_disk
+        # @return [Boolean]
+        def self.compare_disk_state(disk_config, defined_disk)
+          requested_disk_size = Vagrant::Util::Numeric.bytes_to_megabytes(disk_config.size)
+          defined_disk_size = defined_disk["Capacity"].split(" ").first.to_f
+
+          return defined_disk_size == requested_disk_size
+        end
+
+        def self.create_disk(machine, disk_config)
+          guest_info = machine.provider.driver.show_vm_info(machine.id)
+          disk_provider_config = disk_config.provider_config[:virtualbox]
+
+          guest_folder = File.dirname(guest_info["CfgFile"])
+          if disk_provider_config
+            if disk_provider_config.include?(:disk_type)
+              disk_ext = disk_provider_config[:disk_type].downcase
+            end
+          else
+            disk_ext = "vdi"
+          end
+          disk_file = "#{guest_folder}/#{disk_config.name}.#{disk_ext}"
+
+          # TODO: Round disk_config.size to the nearest 512 bytes to make it divisble by 512
+          # Source: https://www.virtualbox.org/ticket/5582
+          LOGGER.info("Attempting to create a new disk file '#{disk_file}' of size '#{disk_config.size}' bytes")
+          machine.provider.driver.create_disk(disk_file, disk_config.size, disk_ext.upcase)
+        end
+
+        def self.resize_disk(machine, disk_config, defined_disk)
+          # check if vmdk (probably)
+          # if so, convert
+          # then resize
+          # if converted, convert back
+          # reattach??
+          # done
+        end
+
         def self.vmdk_to_vdi(driver)
+          LOGGER.warn("Converting disk from vmdk to vdi format")
         end
 
         def self.vdi_to_vmdk(driver)
+          LOGGER.warn("Converting disk from vdi to vmdk format")
         end
       end
     end
diff --git a/plugins/providers/virtualbox/driver/base.rb b/plugins/providers/virtualbox/driver/base.rb
index 9688563d8..168468bc8 100644
--- a/plugins/providers/virtualbox/driver/base.rb
+++ b/plugins/providers/virtualbox/driver/base.rb
@@ -419,6 +419,18 @@ module VagrantPlugins
           execute("modify#{MEDIUM}", disk_file, '--resize', disk_size_in_mb.to_s)
         end
 
+        # Creates a disk. Default format is VDI unless overridden
+        #
+        # Note: disk_size must be divisible by 512 bytes, otherwise operation will fail
+        # Source: https://www.virtualbox.org/ticket/5582
+        #
+        # @param [String] disk_file
+        # @param [Integer] disk_size - size in bytes (MUST BE DIVISIBLE BY 512 bytes)
+        # @param [String] disk_format - format of disk, defaults to "VDI"
+        def create_disk(disk_file, disk_size, disk_format="VDI")
+          execute("createmedium", '--filename', disk_file, '--sizebyte', disk_size.to_s, '--format', disk_format)
+        end
+
         # @param [String] uui - virtual machines uuid
         # @param [Hash] disk - disk to attach
         def attach_disk(uuid, disk)