What you’re seeing
- Extend Volume is grayed out for the C: drive in Disk Management.
- Unallocated space appears at the end of the disk, separated from C: by a small recovery partition of several hundred megabytes.
- The disk was enlarged in the hypervisor or cloned to a bigger drive, but C: stayed the same size.
- Low free space warnings for C: continue even though the extra capacity is sitting on the disk.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- Windows can only grow a volume into unallocated space that sits directly after it, and the recovery partition is in the way.
- Setup on many Windows versions places the recovery partition after C:, and later feature updates sometimes create a new one there.
- The partition holds the Windows Recovery Environment, so Windows protects it from being moved or removed casually.
- The disk uses the older MBR layout, which limits the number of primary partitions and the usable size of the disk.
Why it matters
The space you paid for is unusable until the layout is sorted out, so the original low-disk problem continues. A nearly full C: drive causes failed updates, sluggish performance and, on servers, applications or databases that stop writing data. Removing the recovery partition carelessly can also break features you may need later, including Windows reset and some BitLocker recovery scenarios, and any partition change done wrong risks the data on the drive.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Will we lose the ability to recover Windows if that partition changes?
Not if it's handled properly. The recovery environment can be relocated or rebuilt so it keeps working, and we confirm it's functional before closing the ticket.
Is the data on C: at risk?
Any partition change carries some risk, so we make sure a current backup exists before touching the disk layout.