I use windows server 2008r2 with role Hyper-V. The guest system is Ubuntu 12.04 LTC. It is situated on the dynamic virtual hard disk. I want to compact this VHD (The real size is 50 GB, 360 GB on the disk). But I can not do this, because the Ubuntu file system is not NTFS. What do I need (gparted, sdelete, ...) for solving this problem? The main problem is that the filesystem is not NTFS, but ext4.