I use Macbook Air and Lion. I use Time Machine to back up on my Drobo FS. All seems to be ok until I use Parallels. The Time Machine seems to take my virtual machine as one file so every time I open it Time machine wants to back up the WHOLE virtual machine although I maybe have changed only a word in a file. This leads to huge back ups of 20-30 G. Is there anything I can do about this unnecessary backup? Or is there any way I can tell the Time Machine not to back up my Windows files? Can I use tmutil and in that case how?