Extend drive C: or add a new disk on Windows Server

More disk space on a Windows VPS or VDS arrives as raw storage: either as unallocated space at the end of the existing disk, or as a new disk. Windows does not add it to drive C: on its own. This guide covers both cases on Windows Server 2016 to 2025, including the recovery partition that often blocks Extend Volume.

Before you start

• Order the space: open the server under Services › My Services, then Actions › Upgrade/Downgrade Options for extra disk space or Upgrade/Downgrade for a bigger plan; see upgrade or downgrade a service.
• Take a snapshot or a backup. Windows VPS plans include free snapshots; take one before you change partitions.
• Sign in over Remote Desktop with an administrator account; see first steps on a Windows server.

Step 1: See where the new space is

Open an elevated PowerShell (right-click Start, then Terminal (Admin) or Windows PowerShell (Admin)) and list the disks and partitions:

Get-Disk
Get-Partition -DiskNumber 0

Or open Disk Management (diskmgmt.msc) and choose Action › Rescan Disks. You will see one of three layouts:

• Unallocated space directly to the right of C: follow Case A.
• A recovery partition between C: and the unallocated space: follow Case B.
• A new disk marked Not Initialized or Offline: follow Case C.

Case A: extend C: into the space next to it

In Disk Management, right-click C:, choose Extend Volume, keep Maximum available and finish the wizard. Or in PowerShell:

$size = Get-PartitionSupportedSize -DriveLetter C
Resize-Partition -DriveLetter C -Size $size.SizeMax

Verify: Get-Volume -DriveLetter C shows the new size, and File Explorer lists the larger C:.

Case B: a recovery partition blocks Extend Volume

Windows can only extend a volume into unallocated space immediately after it. A small recovery partition behind C: stops that. The fix moves Windows RE onto C:, removes the partition and then extends C:.

1. In an elevated Command Prompt or PowerShell, check and disable Windows RE. When it is disabled, its image is kept in C:\Windows\System32\Recovery:

reagentc /info
reagentc /disable

2. Start diskpart, find the recovery partition and delete it:

diskpart
list disk
select disk 0
list part
select part 4
delete partition override
exit

Replace 4 with the number of the partition of type Recovery that sits after C: in your list part output.

3. Extend C: as in Case A.

4. Enable Windows RE again. Without a recovery partition, it uses the image on C:

reagentc /enable
reagentc /info

Verify: reagentc /info shows Windows RE status: Enabled, and C: has the new size.

Case C: bring a new disk online

A new disk is empty and may be offline. Find its number (here 1), bring it online if needed, initialise it with GPT, create one partition and format it with NTFS:

Get-Disk
Set-Disk -Number 1 -IsOffline $false
Initialize-Disk -Number 1 -PartitionStyle GPT
New-Partition -DiskNumber 1 -UseMaximumSize -AssignDriveLetter | Format-Volume -FileSystem NTFS -NewFileSystemLabel "Data"

Skip Set-Disk if the disk is already online. In Disk Management the same steps are: right-click the disk, Online, Initialize Disk (GPT), then right-click the unallocated space and New Simple Volume.

Verify: Get-Volume lists the new drive letter with the label Data, and you can create a folder on it.

Troubleshooting

Get-PartitionSupportedSize shows the same maximum as the current size. The unallocated space is not directly after C: (see Case B), or Windows has not seen the new size yet: run Rescan Disks in Disk Management.

delete partition stops with "Cannot delete a protected partition without the force protected parameter set". That is expected for a recovery partition, which is why the command above adds override. Never use override on any other partition: the EFI system partition and C: itself are needed to boot.

reagentc /enable reports an error. Check that C:\Windows\System32\Recovery\Winre.wim exists. If it does not, Windows RE cannot be enabled from C:; the server still runs normally, and you can restore from your snapshot if you need Windows RE.

The new disk does not appear at all. Choose Action › Rescan Disks; if it is still missing, open a ticket with the output of Get-Disk.

Next steps

• Keep Windows up to date after the change: fix Windows Update problems.
• Linux servers: use new disk space on a Linux server.