Parallels vs Vmware Fusion for running Windows on Mac OS X

I've used each and currently use Parallels.

Originally I went with Parallels since it was the first. Then I switched to VMWare since it used to have the better memory management. And now I use Parallels again.

VMWare tends to be more polished and have fewer annoyance bugs but, currently, Parallels is faster (I think I read 20%) and has better memory management. I run Windows Server 2008 as a workstation and primarily do software development with Visual Studio in there.

I did notice a big improvement when I switched to Parallels, but I also switched to Windows Server 2008 from Vista at the same time. YMMV.

BTW, no matter which product you go with, RAM is the most important resource. Try and get at least 4gigs in your Mac and allocate around 1.5 to 2 gigs to Windows.

Also, avoid using the 3D acceleration in either product unless you know you need it. I've had tons of issues with it...

If you really want good performance, you might want to ditch the VM approach and go with Boot Camp, which is essentially a partitioning tool with some extra software that makes it easy to switch between OSX and Windows. You'll have to reboot into Windows of course, but it will make full use of your system hardware and also bypass the audio / video driver problems that always seem to crop up with VMs in my experience.

Ok, here is the skinny.

You should choose VMware Fusion if any of the following apply to you:

• You use VMware Server / ESX / Workstation / Player elsewhere.
• Use the VMware appliances from VMware's website.
• You wish to create VMware appliances.
• You have stock in VMware, Inc.

Otherwise you can use Parallels, or may I suggest Virtualbox? Parallels and Virtualbox tend to have better performance than VMware across all platforms that I have used (Virtualbox: Linux, Windows, OS X) (Parallels: OS X).

On another note, you won't find any benchmark stats comparing VM software because VMware's licenses forbid the posting of benchmark stats without their permission.

If this anecdotal evidence is worth anything, on OS X 10.5.6 and VMware Fusion 2.0.4 I have been having major Windows Server 2003 file system corruption and OS X kernel panics. Happened 3 times in the past week, having to reinstall everything multiple times. Either way you go, be sure to use the snapshot features!

I have used both a little. If you are using Vmware on your servers, then creating Vmware VMs is a useful advantage.

I've not had a great deal of experience with Parallels so can't really compare it with VMware Fusion. I use VMware Fusion daily at home and I picked it mainly because at work I use Windows hardware running VMware Workstation and any virtual machines it uses, I can easily use in VMWare Fusion. The format is very portable like that.

In terms of performance, I'd say the VM's tend to run slightly faster on Mac than on PC. Also, as brendanjerwin mentions, memory is important. I run a simple Windows XP VM with 512MB and that runs great. My work VMs tend to have 1GB to 1.5GB allocated, and again, they run well with VMware Fusion.

Also, if you're going to run VMs, put them on an external hard drive, as Jeff Atwood has suggested previously, since that'll help with drive access. Running VMs off of a local drive can really kill performance as you can end with contention with the main OS. I've run off both large capacity 7200rpm drives and small 5400rpm passport drives with no problems.

I know that's a bit away from what you were asking, but thought it might be relevant.