Neil Turner's Blog

Blogging about technology and randomness since 2002

How to migrate a Parallels virtual machine to VirtualBox

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:

1. Back up your virtual machine

Seriously. We’ll need to modify it a bit before it’s converted, so you’ll want a backup copy just in case things go wrong, or if you may use Parallels again in future.

2. Uninstall Parallels Tools

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.

3. Close all programs

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.

4. Install VMWare Converter

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.

5. Go and grab a cup of coffee

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.

6. Shut down the machine in Parallels

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 which won’t allow multiple instances.

7. Import the disk into VirtualBox

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.

8. Boot up in VirtualBox

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.

9. Install VirtualBox Guest Additions

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’ and follow the on-screen instructions. Though this is optional, it will improve the experience of using Windows in VirtualBox.

Hopefully now you’ll be up and running in VirtualBox. Feel free to post comments below and I’ll try to do what I can to answer them but I’m not the world’s greatest expert in this. I also don’t know how to do this in other versions of Windows or other operating systems.


  1. Hi,
    my question is a little bit out of topic, but do you know something about speed comparing this 2 apps?
    i currently have installed vbox and parallels (demo) on my mac, but i seams vbox is much slower. could this be possible? perhaps because vbox doesnt support the vt-x extension of my macbook? as guest system i run a fedora 10 beta system.

  2. VMWare Converter creates sparse disk images (the main image is split into multiple 2GB images like WinXP-s001.vmdk, WinXP-s002.vmdk, etc…) VirtualBox doe not handle these afaik. The only way I’ve found to convert these to a single monolithic file is using a small binary that’s included as part of the VMWare Server (which is a 500MB install).
    So this doesn’t really seem to be a viable solution… How did you get a single hard drive image from the converter? What version were you using?

  3. officialtrash: VirtualBox 2.0.4 handles the sparse files fine.

  4. I was unsuccessful in starting my converted Windows XP image from Parallels in VirtualBox. Even Safe Mode with Console gives me a blue screen. It’s only there for a tenth of a second, but I managed to grab a screen shot:

  5. Henrik: has some information about that error but it may be you didn’t get all of the text in the screenshot. If it’s a device driver error it should give you the file name of the driver that caused the error.
    Did you uninstall Parallels Tools (and restart the virtual machine) before migrating? And was the virtual machine originally a Boot Camp partition?
    Patrick: I haven’t used VirtualBox enough to be able to do a full speed comparison. I’ve seen mixed results from others; some say VB is faster than Parallels, some vice versa.

  6. Thanks for the link, Neil. I did uninstall Parallels Tools before migrating, I also rebooted before migrating. The VM was not a Boot Camp partition, just a regular Parallels image.
    I wasn’t able to get a better screen shot of the blue screen since it’s only the for an extremely short time. Here’s the last console output before the blue screen: . What should happen after Mup.sys?

  7. I managed to get all of the info from the blue screen:

  8. I had the same issue. The problem has to do with some validation that Windows does on hard disk controllers. Virtualbox has a link on Windows migration at that has a link to a utility called MergeIDE. Essentially it is a batch file and a reg file. The utility is written in German. I ran it in my Parallels VM before I did the vmware export (the second time) and all was good.

  9. Thanks raul! MergeIDE ( ) was all I needed, it worked flawlessly. (Not entirely correct since I needed to fetch my long lost serial number to re-activate Windows again, but that’s another story.)

  10. Silly question here:
    If I uninstall Ptools, I loose any network capabilities as well as the local mount to the Mac hard drive.
    How do you then save these files to a hard drive outside the VM?

  11. Silly question here:
    If I uninstall Ptools, I loose any network capabilities as well as the local mount to the Mac hard drive.
    How do you then save these files to a hard drive outside the VM?

  12. I encountered the same problem!
    As soon as I uninstall PTools, it also uninstalls the needed network card drivers, which means that I don’t have Internet or any connection to my Host system (Mac) anymore.
    Therefore I don’t have a chance to save the converted image on my Mac Partition.
    May this be a Problem of the newest Parallels 4.0 version only?

  13. I’ve had the same as anthony and h3lli about the loss of network connection when uninstalling Parallels Tools (v 3.0).
    Has anybody a solution for that?

  14. @anthony, h3lli, Mathieu:
    An easy workaround is to attach another virtual hard disk to your Parallels machine and have the VMware Converter store the converted VM image there. Afterwards you can use the Parallel Explorer tool to extract these files from the virtual disk image into the Mac filesystem.

  15. I am using Virtual Box 2.2.4 and I used this method to convert a Parallels 4 Windows XP machine. Unfortunately, VirtualBox can’t seem to read the sparse images. It says:
    “Could not get the storage format of the hard disk (VERR_NOT_SUPPORTED)”

  16. I get exactly the same problem with the same version of VBox as KM, any advice or assistance would be hugely appreciated. Could save me hours setting up all my VMs again.

  17. Hi Niel, does this post seem similar to yours: Incredible this Brandon Wirtz…