Platform Peace

So, what virtualization software should you use to run Windows simultaneously on Mac OS X?  Well, the good news is that the two primary choices, Parallels Desktop and VMWare Fusion, are both excellent options and the choice really just comes down to personal preference and your intended usage.

There are several reviews and comparisons you can read about so I will not rehash them here.  I did a (very) brief evaluation of both products before I made a decision.  From the start, VMWare had an advantage in my mind for a few reasons:

1. I already have a few VMWare virtual machine images that I regularly use and that could immediately be used under Fusion without any type of conversion process.
2. Fusion provides better support for other operating systems besides Windows.  This is important if you want to run Linux for example.
3. I have used VMWare products happily for a number of years.

So, all other things being equal, I would have picked Fusion and I wasn’t expecting to have a tough decision.  But, I did want to give Parallels a quick try.

Integration

What I found was that Parallels provides a number of a number of nice, user-friendly features that make running Windows in Mac OS X a much more integrated and consistent experience.  Both products offer the ability to run a Windows application within OS X as if they were a native Mac application (the other options include running the entire virtual machine in a window or full screen).  In Parallels, this mode is called Coherence and in Fusion it is called Unity.

The behavior of Fusion’s Unity mode seems inconsistent.  Overall, it works pretty well and you can have a Windows application running as what appears to be a normal Mac OSX application.  However, the way it integrates within OS X is not perfect.  Sometimes, the application icon will show up in the dock; other times it will not. 

(Click for a larger image.  Note that I am running Windows Live Writer and IE7 in the foreground but only the icon for Windows Live Writer shows up in the dock.)

Also, a huge disappointment in Unity mode is the lack of multiple monitor support.  If you are running in Unity mode, your Windows applications can only run on the same monitor you are running the main Fusion application on.

Parallels’ Coherence mode seemed to work much more consistently and provided a much more integrated experience.  Applications consistently showed up in the dock and Windows applications could be used fine across multiple monitors.  Parallels also has a number of other features that make using Windows in a Mac a more seamless experience.  One I particularly liked was being able to mount the Windows file system directly within OS X.

Note that both programs have the ability to use a boot camp partition as a virtual machine.  This means you can install Windows on a boot camp partition and boot straight to Windows if you need to or use the exact same Windows install as a virtual machine while you are in OS X.  I did not try this option since I am expecting a virtualized Windows instance to provide the functionality and performance I require.  However, this is a nice feature and is something I may try down the road (maybe with Leopard).  This is a particularly good option for gamers.  I’d love to hear about anyone who is doing this now with success, particularly with Vista.

Performance

Although I didn’t do any scientific performance testing, my anecdotal experience suggested that Fusion performed noticeably better than Parallels.  This is consistent with the testing done by CNET here and probably has a lot to do with Fusion taking advantage of both CPU cores. 

Conclusion

Along with the initial three reasons listed above, performance was the deciding factor in my ultimate choice of Fusion.  Although some of the features in Parallels make it a more user-friendly and more tightly integrated option, my primary concern was performance and Fusion seemed the better fit there.  Hopefully, VMWare will fix some of the UI and integration flaws in future releases.  In either case, I don’t think you can go wrong with either product and I am sure they will continue to improve in subsequent releases.