Extend System Partition on a Windows Server 2003 VM using Dell ExtPart

There is no native tool that enables extending system partitions (C:\ drives) on Server 2003. There are multiple ways to perform this task, however, the only method that can be done online utilises a Dell utility called ExtPart. It can perform the extension of the system partition with no downtime although sometimes booting into Safe Mode and then running ExtPart is necessary to clear locks on the disk.

Note: This applies to Server 2003 only, newer versions of Windows do not suffer from this limitation, Disk Management as well as the diskpart are able to extend system partitions on-the-fly.

The first step is to download the ExtPart utility from this link. Click on the Download File link and save it to your desktop. The file is a self-extracting zip file called ExtPart.exe per the below:


Double-click on it and accept the default path it will extract the utility to:


Click on Unzip and the files will be extracted successfully:


To demonstrate how useful ExtPart is we will use an example whereby our demo VM has a 15 GB C:\ drive and it needs to be increased to 30 GB. A screenshot of the the current state of the C:\ drive is below:


We go into the VM settings and can see that the virtual disk is indeed 15 GB in size:


We increase the virtual disk size to 30 GB and apply the change:


Within the VM load Disk Management and select Action > Rescan Disks so that the system sees the newly added 15 GB of storage:


After the re-scan completes you will now see the extra 15 GB of unallocated space:


Now we need to run the ExtPart utility expand the C:\ drive so that it utilizes the 15 GB of unallocated space. To proceed, open the command prompt and go to the location where you extracted the ExtPart utility, in my case, C:\dell\ExtPart:

C:\>cd C:\dell\ExtPart

Then run ExtPart.exe:


Enter the volume that is being expanded, in this example it is the C:\ drive so enter just C: without the backslash:

Volume to extend (drive letter or mount point): C:

Then enter the amount in MB to increase the volume by, I entered 15343:

Size to expand the volume (MB): 15343

The output will confirm the new size of the volume (C:\ drive), which is 30678 MB:

New volume size          :30678 MB (32169069568 bytes)

The full sequence of commands can be seen in the screenshot below:


When going back into Disk Management and re-scanning the disks, we can see that there is still 31 MB that is unallocated:


To add that remaining 31 MB to the C:\ drive, we go back to ExtPart and perform the same series of steps but this time add 31 MB:

Size to expand the volume (MB): 31

A screenshot of those steps is below:


Now going back into Disk Management you can see that the C:\ drive is using all of the provisioned space in the disk:


If the utility returns an error such as “the disk is not accessible” or “unable to connect to C:” then reboot the VM into Safe Mode and then run the same ExtPart commands. This is caused by various services locking the disk and preventing ExtPart from extending the volume. Booting into Safe Mode starts up the OS in a clean state, so only minimal services and drivers will run, thereby allowing ExtPart to expand the volume without interruption.

  • Sarah Clinton

    usually if there is unallocated space contiguous to system partition, you can extend system partition in server 2003 with disk management. if there is no unallocated space contiguous to system partition, the extend volume will gray out and you are not allowed to extend partition.

    in this situation, i suggest you use free third party software for server to extend partition.

    more information:


    • japinator

      Indeed, I should have made that clearer in the post. In the cases that I have had to use the method above there has not been contiguous unallocated disk space adjacent to the system partition. Unfortunately this precluded the use of the disk management tool, furthermore, diskpart cannot extend system partitions at all in server 2003. For me ExtPart is a tried a tested tool, so is GParted which I have used for offline shrinks and extends on Server 2003. Thank-you for your comment and the link to the partition tool.

  • Musal

    Worked fine ! Great job many thanks

    • http://www.vsysad.com japinator

      Good to hear :)

  • http://www.anthonymaw.com/ Anthony Maw

    yeah this utility works great. if you don’t have about 2 GB of free disk space the .Net updates will fail to install.

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  • Ignatius

    Thanks for this page! You’re a lifesaver! It worked great! Hopefully we’ll be getting rid of this Server 2003 VM, but until then this gave us a lot more breathing space.

    • http://www.vsysad.com japinator

      Glad to hear it. I was in exactly the same position as you and ExtPart saved me a lot of trouble.