Time Machine and VMware Fusion

I upgraded to Windows 7 today on my Fusion Virtual Machine on my Macbook today. I preceded it with a Time Machine backup, and it copied a few gigabytes, which I expected since I installed CS4 the other day.

Two hours later...
I installed the Windows 7 upgrade, and then did another Time Machine backup. This time it copied 36 gigabytes (the amount of my virtual machine file).

This got me thinking... Does Time Machine backup the entire virtual machine file each time there is a slight change? If so, then merely launching Windows in Fusion would be enough for Time Machine to backup the virtual machine file, using almost 40 gig on my backup drive most every time I launch time machine backup, even though the change is minor (a few bytes)

The consequence is that for a Fusion user, the backup device is going to fill awfully fast because of the relatively minor changes to the VM file, thus making for paltry space for history on all the Mac files.

I figure that a 320 Gig backup device is effectively extremely tiny for a 250 Gig HDD with only 90 Gig of files. My backup drive is already full after only ~8 backup sessions, hence deleting old history, which is hardly a few months old!

Amy I missing something here?

 

No, you're not missing anything. I usually take out the VM's from a TM backup. You can always back them up separately.

 

VMs are whole files. The mechanism that tells Time Machine which files were modified only keeps tracks of whole files, not parts of the files.

 

I'd go with Vogelbung's solution and exclude the VMs in Time Machine.

Personally, I only have TM back up my apps, document files and general OSX stuff so that if I have to reformat my OS is back to normal. Then just I back-up my music/videos/large files separately as it would eat up the back-up drive's space real quick as you mention.