In Disk Management, you can extend boot partition and data partition in contiguous unallocated space.
Do the following steps to open Disk Management:
Do as follow:
Contiguous unallocated disk space: unallocated space followed the volume you want to extend; the position is on the right side of target partition; if there's no such space to distribute, you can delete the right position partition or shrink the partition to make one.
However, shrink volume is not helping on boot partition extension, because the unallocated space made from Shrink Volume is not in the right side of boot partition. You cannot move unallocated space in Disk Management until you use other free server partition tool. Extend Volume Wizard in Disk Management is a downwards extension wizard used under certain conditions.
If there's no contiguous unallocated disk space, you：
1. Can't Extend Volume in C Drive
2. Can't Extend C Drive to Unallocated Space
3. Unable to Extend Unallocated Space
4. Unable to Extend Partition
Those are the limitations in Disk Management, if you want to add unallocated space to C drive, you have to move the space to the right side of boot partition, then use Extend Volume to Unallocated Space, so Windows Server users don't use the default tool to manage disk space when the four listed common situation happens.
Partition Extender will：
If you have much space in each partition, you can shrink them into many unallocated space in Disk Management or Disk Partition Expert, then use Partition Extender to extend boot partition with one click. See how to move space in Disk Partition Expert.