virtualbox.org

I'm running on a windows 7 pro host and have created immutable images for Windows server 2012 and Ubuntu Server / Desktop and lastly for Windows 7 guests.
The Ubuntu and WIndows server immutables are 12 GB or less in size. But the Windows 7 is 92 GB (NINETYTWO GB).

The immutable images are all dynamically allocated. Once I have the base installed on them I set them to read only.

The Windows 7 immutable has an initial disk size of 128 GB. But again, it's dynamically allocated.

Anyone any idea why this would be happening?

Cheers!

It happens because you created a disk >=92GB in logical size, and a process inside the guest wrote 92GB of data to the drive.

I suggest that you compact the disk before making it immutable.