After adding drives to an array, or expanding a Games or System image by adding additional space, the additional space is not displayed in Windows.
Click the Start Button, type "Disk Management", then click the "Create and format hard disk partition" Control panel in the "Best match" category to launch the "Disk Management" snap-in.
Within the "Disk Management" snap-in, locate a disk which shows unallocated space. This is a drive that needs to be expanded.
Within the "Disk Management" snap-in, locate the partition to the left of the unallocated space. This is the partition within the drive that needs to be expanded.
Right-click on the partition that needs to be expanded, then select the "Extend Volume..." context menu item.
Within the "Extend Volume" wizard, on the "Welcome" page, click the "Next" button.
Within the "Extend Volume" wizard, on the "Select Disks" page, click the "Next" button to accept the default, which is to extend the volume to fill all available space.
Within the "Extend Volume" wizard, on the "Completing the Extend Volume Wizard" page, click the "Finish" button to commit the changes to the partition table.
Observe that the Volume has now been successfully expanded to fill the previously-unallocated space on the drive.
This process is similar to a situation you would run into as a Windows administrator when a smaller drive is cloned to a larger drive that is then installed in the system. Windows is aware of the space that has been added to the drive, however by default nothing is done with the added space.