mpack,thanks for that awesome tool. Running under wine as no problem at all. It saves just an enormous amount of time. Before I found your tool, I was e.g. trying to reduce the size of a Windows 7 64bit VM down from 58 GB. The allowed size was 159 GB. I first tried nullfile, which took forever and did not help. At one point I noticed that probably due to some mistake I had made, it actually was trying to write a huge file on my host system. I ended up finding a 500 GB or so file. Nice. Next, I tried sdelete -c, and then vboxmanage -compact, which ended up giving me a file that had gone up to its maximum size, i.e., 159 GB. That option, too, take several hours and, of course, did not help at all.Then enter CloneVDI. apt-get install wine, then go to the folder which holds the disk file, choose it, and go. Just for fun, I ran it on the 159 GB file, later also on the original 59 GB file - which made no difference really. So with your tool, I could collapse 159 GB into 36 GB in under 5 minutes:, imperia, rolex submariner nero eta clone swiss made euro 700, CloneVDI isn't copying the file, it's creating a new file with the same content, rearranged for efficiency. If you think you can create a streaming DMA copy algorithm that can do that, then be my guest!.