Oracle's VirtualBox hypervisor runs as an application on your OS X devices, allowing you to can run a virtual machine inside the application. You can specify how much disk space to give to that virtual machine, and load another operating system on it. There are two post-installation configuration issues you might run into: getting VirtualBox to play nicely with modern screen resolutions -- especially with Retina Display devices -- and increasing the amount of disk space allocated to a given VirtualBox instance on your computer.

Adjusting Screen Resolution

Step 1

Search for "," one of the configuration files for VirtualBox. It resides in your VirtualBox folders, but depending on the version of VirtualBox you have installed, it may be in the Extra or SystemConfiguration subfolder.

Step 2

Make a backup copy of this file by copying and pasting it somewhere else.

Step 3

Open the original file with a text editor.

Step 4

Search within the file for "Graphics Mode," which should be in XML tags. Underneath the tag containing the element "Graphics Mode" there's a String tag containing the element "1280x1024x32" or something fairly similar. That string contains the pixels and color depths that VirtualBox uses for your display. Change that to whatever resolution your OS X machine supports.

Step 5

Save the file. Make sure to uncheck the check box that says "save with a .txt extension" to save it with the .plist file extension.

Step 6

Start VirtualBox; it now uses the new screen resolution.

Resizing the VirtualBox Disk

Step 1

Back up your existing virtual drive, or VDI, file by starting the VBoxManage utility in VirtualBox, and then entering the following command at the command prompt:

clonehd <path to your original vdi file> <path of the copy>

This may take a few minutes to complete.

Step 2

Resize the virtual box drive by typing the following command into VBoxManage:

modifyhd <path to your vdi> --resize <new size in megabytes>

Note that the "resize" flag has two hyphens preceding it. Remember that there are 1024MB in a gigabyte.

Step 3

Shut down and restart VirtualBox to access the additional disk space.