virtualbox.org

Hi,

I have a Virtual Guest with a virtual hard disk of 20GB which are allocated dynamicaly.
Since now it reaches the physical/real size of about 19.4GB.

Now that I have deleted a lot of files within the guest,
I think it would be great if I can re-compress the vdi file to a lower size as it was before.
Is there a way to do so?

Depends on the host and the guest. Without more information it would be hard to say.

My Host is a Windows 7 (Uptodate)
Guest is WindowsXP up to date.
VirtualBox 4.2.6 r82870

Perhaps the best tool for Windows VBox users CloneVDI Tool
Safest as well as the original is not changed at all. Once you have your compressed clone you attach it to the drive instead of the original and fire it up. After you have verified it works you can delete the original or better yet keep it as a backup.

If you have snaoshots, here again not mentioned, you need to be sure to clone the current state (read the docs in the tool)