Despite Parallels and VirtualBox both being programs which run virtual machines on Mac OS X, they both use different file formats for storing the virtual machines on disk. Though I believe Parallels will open a VirtualBox disk, VirtualBox cannot automatically import Parallels disks. But it’s not impossible…
If the guest operating system, i.e. the system that is running inside Parallels, is Windows 2000/XP/Vista, then it is possible to use a free tool from VMWare to do the conversion. Here’s a step-by-step:
Seriously. We’ll need to modify it a bit before it’s converted, so you’ll want a backup copy as otherwise it might not be as useful.
This is the modifying bit. Load your Windows virtual machine in Parallels, and uninstall Parallels Tools (the helper program that adds drivers and clipboard sharing, and other stuff). This is important as otherwise your virtual machine won’t boot in VirtualBox – and I know this from experience. You also can’t uninstall Parallels Tools unless you are running Parallels at the time.
Close as many running programs in your virtual machine as possible. We’re about to take a snapshot image of it while it is running, so any unsaved data may be lost when you boot the image in VirtualBox. That includes programs with icons in your notification area, such as virus scanners, instant messaging programs etc.
Once Parallels Tools has been uninstalled (you may need to reboot the virtual machine for this), we can begin the conversion process using a tool ironically made by VMWare. Go to the download page for the VMWare Converter in whatever web browser you use in your virtual machine (it’s a Windows program) Download it, and then install it.
Run the Converter tool, and click ‘Convert Machine’ – this should pop up a wizard which walks you through the process of setting up a new virtual machine image. You want to tell it to use a ‘Physical Computer’, and then on the next screen choose ‘This Local Machine’. Select the hard disk of the virtual machine and leave ‘Ignore page file and hibernation file’ ticked as this will just bloat the new virtual disk with unnecessary rubbish.
For the type of virtual machine, select ‘Other virtual machine’, and on the next screen, give it a name (e.g. ‘Windows Vista’). You will also need to save it somewhere, and this should not be the existing hard disk of the virtual machine. You can either use your Mac’s main hard disk, mapped to drive ‘Z:’ under Parallels, a network drive or an external drive if you have it forwarded through to the virtual machine. You should be able to use the top option for the type (i.e. ‘Workstation 6.x’) but if it doesn’t work try another option. Keep ‘Allow disk to expand’ checked on the next screen. Click through until you’re ready to complete, and start the conversion.
Or go out shopping. Or read a few chapters of War and Peace. Either way, the machine will take a significant amount of time to convert – mine took around 45 minutes and was only around 15 GB. Bigger disks may well take longer. It helps if you don’t have lots of other programs running on your Mac at the same time as then more of your CPU juice can be used for the conversion.
Now that you’ve exported the machine, shut down Windows and close Parallels. This is mostly so that you can stay within the terms of the license agreement for Windows.
Open VirtualBox, choose ‘File’ and then ‘Virtual Disk Manager’. Add the disk file that you created, and click OK. Then click ‘New’ to create a new virtual machine, and select the correct operating system from the list. Try to ensure that you give the virtual machine the same settings (such as RAM size) as you did in Parallels. When asked for a hard disk, click the ‘Existing’ button and choose the disk file that you created from the list. Then click Finish.
Hopefully all will have gone to plan, and you will be able to boot into Windows as before. All of your files and programs should be there waiting for you.
If, however, you encounter a blue screen mentioning ‘prlfs.sys’ like I did, boot the machine but press F8 during the boot to enter Safe Mode with Command Prompt. Type in cd c:\windows\system32\drivers and then rename prlfs.sys prlfs.sys.old and then reboot – that should get you up and running. For the inquisitive, prlfs.sys is part of Parallels Tools and this should have been removed as part of step 2, however muggins here forgot to this when he tried it himself and therefore encountered this error.
Guest Additions are to VirtualBox what Parallels Tools are to Parallels – in other words, they make Windows sit better in the virtual machine and improve integration with the host operating system. On the main VirtualBox menu, select Devices and then ‘Install Guest Additions’