VirtualBox
Table of contents
How to reclaim space / compress virtual disks
1. Defrag your disk inside the VM2. Overwrite unused space - use tool from Link #2 (SysInternals SDelete)
SDelete -c
3. Compact the virtual disk
VBoxManage modifyhd diskimage.vdi --compact
How to clone a virtual disk (the right way)
VBoxManage clonehd diskimage.vdi newimage.vdi
How to clone and convert a virtual disk to VMDK format
VBoxManage clonehd diskimage.vdi diskimage.vmdk --format vmdk
Links
1. http://www.virtualbox.org/
2. http://technet.microsoft.com/en-us/sysinternals/bb897443.aspx
3. http://blogs.sun.com/virtualbox/entry/how_to_compact_your_virtual
(great inspiration)