VMWare Fusion, OS-X and Large Files

August 19, 2008

I’ve been using VMWare Fusion running an XP Virtual Machine on my Macbook Pro for 9 months now, and it’s been rock solid. There are reasons (corporate) why I need to have a specific XP build for accessing certain business support systems hence why I’ve not made the OS-X conversion all the way. I’ve been trying to replicate my XP VM onto another external drive. The image is 40GB. Computers says NOOOOOO !

I was receiving an unhelpful Error 0 from the drag-n-drop copier in the OS-X Finder, and when I dropped to a terminal window it was copying around 4 gigabytes before complaining the file was too large….yeah…it made me wait before telling me that ! So how do I move a large file?

I checked out VMWare forums who recommended using vdisk-manager (and it’s many complicated parameters) to chunk the image into 2GB files. There was also chatter of using the VMWare Fusion advanced applications settings to set the flag to ‘break image into 2GB files’ but it turns out that option is only relevant to newly created image files.

To cut a long and painful story short, after trying many weird and wonderful options, I used the following command:

# split -b 2048m /Users/Name/Documents/Virtuals/source.vmdk /Volumes/USB Drive Name/dest

This successfully broke up my 40GB source file into a file-set, using a aa..nn suffix, in my destination like:

# ls /Volumes/USD Drive Name =>

destaa, destab, destac, destad .. destat

I was then able to move my VM onto another host and reconsitute the backup with a neat bit of ruby scripting (as an alternative to a long-winded command-line). Something along the lines of:

cmdline=’cat ‘

for suff in ‘aa’..’at’ do

cmdline << “dest#{suff} “


cmdline << “> source.vmdk”


This a long-running yet simple solution to something I’d been struggling with for a couple of hours, and there was no need for any external tools or complexities.

The copied VM works perfectly too…but I accept no resposibility for anyone who fluffs this approach !

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