By Bryce / Last Updated November 29, 2019

Unable to extend C drive in Windows 2003 Disk Management

“My computer is running Window Server 2003 and the capacity of C drive is 56GB and D drive is 123GB. Now, the C drive is almost running out of space and shows a red bar and there is no unallocated space on the disk. Open Disk Management and I right click D drive but find that there is no Shrink Volume or Extend Volume. Then, how to increase C drive space in Windows Server 2003?"

Extend C drive via a great partition tool [without Data Loss]

To enlarge system drive (C drive) in Windows Server 2003 easily and safely, you can turn to a professional and reliable partition manager for Windows Server, AOMEI Partition Assistant Server. It is featured with a powerful function – Allocate free Space, enabling you to directly allocate free space from one partition with redundant space to the partition that you want to extend. The whole process can be easy and effective. It can also support Windows Server 2019/2016/2012 (R2)/2008(R2).

Now, install AOMEI Partition Assistant Server and have a look at how to increase C drive space in Windows Server 2003 via it.

Step 1. Run the software, right click the partition with enough space (here is D drive) and choose Allocate Free Space.

Step 2. In the small pop-up window, you can adjust the space that you want to allocate from D drive and choose C drive as destination drive. Then, click OK.

Step 3. Go to main console automatically and you can preview the result of operation. If you are satisfied, click Appply and Proceed.

● After executing this operation, some free space will be allocated from the source partition to partition C. In other words, the source partition will be shrunk, and the C drive will be expanded.
● If there is an unallocated space (whether it is contiguous or non-contiguous) on the same disk, you can use AOMEI Partition Assistant Server’s Merge Partitions function to merge unallocated space to C drive.

Increase C drive space in Diskpart [limited]

When there is an adjacent unallocated space behind C drive, you can enlarge it in Windows Server 2003 without employing third party partition software. You can turn to Diskpart utility. Then, refer to the steps given below about how to extend C drive in Windows 2003 using Diskpart utility:

Step 1. Press Windows + R, input "diskpart" and hit Enter to access Diskpart utility interface.

Step 2. Run commands as follows in order:

● list disks
● select disk n
● list partition
● select partition m
● extend size=x


  • “n” refers to number of the disk that holds C drive; “m” is the number of C drive; x is the size n MBR that you want to add.

  • You can type “extend” instead of "extend size=x" to increase C drive partition; if so, C drive will occupy all capacity of the adjacent unallocated space.

  • If there is no unallocated space behind Partition C, you are unable to extend it. Or you can delete the partition behind C drive to create such unallocated space, but this will cause data loss.


Now, surely you have known how to increase C drive space in Windows Server 2003 even there is no unallocated space on the same disk. But if the whole disk is too small to meet your data storage demand, you can replace it with a larger one. To transfer all data including Windows Server operating system, you can clone current disk to new hard drive in Windows Server.