Step1 When you decide to perform an In-place upgrade of Windows Server 2008, you will notice that the installation process requires at least 14062 MB of free space. This means free space, not the size of the Boot Volume. If you do not pass the free space check, you will not be able to proceed with the upgrade. We would like to remind you that according to Microsoft’s terminology, the Boot volume is the disk volume that contains the Windows/Winnt folder ( the Windows operating system files and the supporting files). In Step1, we demonstrate a nice way to extend your Boot volume using the Windows Server 2008 installation disk.