Problem: Not enough unallocated disk space exists on the target computer to enable BitLocker. To deploy BitLocker on a target computer, at least 2 gigabytes (GB) of unallocated disk space is required to create the system volume. The system volume is the volume that contains the hardware-specific files needed to load Windows after the BIOS has booted the computer.
Possible Solution 1: On existing computers, use the Diskpart tool to shrink drive C so that the system volume can be created. In some instances, though, the Diskpart tool may not be able to shrink drive C sufficiently to provide 2 GB of unallocated disk space, possibly because of fragmented disk space within drive C.
One possible solution to this problem is to defragment drive C. To do so, perform the following steps:
1. Run the Diskpart shrink querymax command to identify the maximum amount of disk space that can be unallocated.
2. If the value returned in step 1 is less than 2 GB, clean drive C of any unnecessary files, and then defragment it.
3. Run the Diskpart shrink querymax command again to verify that more than 2 GB of disk space can be unallocated.
4. If the value returned in step 3 is still less than 2 GB, perform one of the following tasks:
· Defragment drive C multiple times to ensure that it is fully optimized.
· Back up the data on drive C, delete the existing partition, create a new partition, and then restore the data to the new partition.
Possible Solution 2: The ZTIBDE.wsf script runs the Disk Preparation Tool (bdehdcfg.exe) and configures the system volume partition size to 2 GB by default. You can customize the ZTIBDE.wsf script to change the default, if necessary. However, modifying the MDT scripts is not recommended.