After you add disk space to your server, for example with an NVMe disk add-on, Windows does not use the new space automatically. Depending on how the space is added, it appears either as unallocated space on the existing disk or as a new disk. This guide covers both.
Warning: Back up anything important first (guide). Never delete a partition to make room unless you know exactly what it holds; deleting the wrong one can make the server unbootable.
1. Look at the disks
- Press Windows + R, type
diskmgmt.mscand press Enter. - Choose Action → Rescan Disks so Windows picks up the change.
Now look at the bottom panel:
- A black Unallocated block directly to the right of C: → follow Case A.
- A new Disk 1 marked Not Initialized or entirely unallocated → follow Case B.
Case A: extend the C: drive
- Right-click C: and choose Extend Volume.
- Click Next, accept the maximum size offered and click Finish.
Or in PowerShell as Administrator:
Update-HostStorageCache
$max = (Get-PartitionSupportedSize -DriveLetter C).SizeMax
Resize-Partition -DriveLetter C -Size $maxNote: If Extend Volume is greyed out, another partition (often a small Recovery partition) sits between C: and the free space. Windows can only extend into space directly after the partition. Do not delete the recovery partition on a guess; open a support ticket if you are unsure.
Case B: set up a new disk
- If prompted, choose GPT to initialise the disk.
- Right-click the unallocated space and choose New Simple Volume.
- Accept the size, pick a drive letter such as D:, format as NTFS and click Finish.
Or in PowerShell:
Get-Disk | Where-Object PartitionStyle -eq "RAW" | Initialize-Disk -PartitionStyle GPT -PassThru | New-Partition -AssignDriveLetter -UseMaximumSize | Format-Volume -FileSystem NTFS -NewFileSystemLabel "Data"Then point programs at the new drive, for example move database files or website folders to D:\.
2. Check the result
Get-Volume | Format-Table DriveLetter, FileSystemLabel, Size, SizeRemainingTroubleshooting
- No new space appears after rescan: restart the server once, then rescan. If it is still missing, check in the client area that the upgrade has been applied.
- Disk shows Offline: right-click the disk label (Disk 1) and choose Online.