1. I like the idea of running Windows and OSX side-by-side* AND
2. I don’t have enough hard drive space (I run all my VMs off an external drive) AND
3. I haven’t rebuilt my Mac in a long time to free up enough space

• Yes, I am aware VMWare Fusion has the ability to run a VM from the Boot Camp partition and if I ever get around to freeing lots of space from my MacBook or adding a larger capacity hard drive, I might try this option.

With that in mind, I wanted to capture this post of Boot Camp tips from TheAppleBlog for future reference.

Boot Camp: Taking the Sting Out of Your Sin

Looks like I’ll have to wait on the VMWare Fusion 1.1 upgrade.

Just some things I noticed online today.

• First Leopard Update released.  Here is the fix list.
• Quicksilver top 10 plugins.
• Use rsync to emulate Time Machine
• VMWare Fusion 1.1 released.  Release notes here.

One problem I ran into with my new Time Machine setup was that my large virtual machine disk files were aggressively being backed every time they changed.  Since each virtual machine is extremely large (multiple GBs each) and since Time Machine backs up an entire file each time it changes, I was quickly eating up lots of space on my external drive.  Also, since Time Machine had to backup what turned out to be 20+ GBs nearly every hour, Time Machine backups weren’t exactly transparent.  I certainly noticed based on CPU and disk activity that backups were in progress.

Thankfully, there was an easy fix.  As mentioned in the previous entry, Time Machine lets you exclude specific disks, directories, and files from backups.  I keep all my Virtual Machines in "~/Virtual Machines" so I simply added that directory to the exclusion list.

However, one more step remained.  I wanted to free up all the space taken by the virtual machine backups before I noticed the problem.  I opened Finder and navigated to my Virtual Machines directory (actually I invoked Quicksilver and typed "virt" + enter).  I then launched Time Machine (Quicsilver + "Tim" + enter).  From the Gear menu button in the Finder, I selected "Delete All Backups of …" for each of the files and directories I wanted to remove. 

Time Machine will prompt you for confirmation and, if you are not running as a privileged user, will also prompt you for credentials. 

Problem solved.  I excluded my virtual machine backups from Time Machine and freed up close to 100 GBs of space from my drive.

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.