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🛠️ Extend C: Drive on Windows Server When Recovery Partition Blocks Resize

On Windows Server (e.g., 2022) hosted on ESXi, it's common to extend the virtual disk from vSphere, but Disk Management won't allow extension of C: if a small recovery partition exists after it.

This guide explains how to temporarily remove, then recreate, the recovery partition to free up space for extending C:.

Disk layout before extension

✅ Steps Summary

1. Disable Recovery Environment

reagentc /disable

2. Remove Recovery Partition with Diskpart

diskpart
list disk
select disk <#>
list partition
select partition <#>   ← identify the Recovery partition
delete partition override
exit

3. Extend C: Drive

  • Open Disk Management
  • Extend the C: partition leaving ~1024 MB of unallocated space at the end
    (this is needed for re-creating the recovery partition)

4. Recreate Recovery Partition

  • In Disk Management:
  • Create a New Simple Volume in unallocated space
  • Format as NTFS, no drive letter

5. Mark the New Partition as Recovery (Diskpart)

diskpart
list disk
select disk <#>
list partition
select partition <#>   ← the new 1024 MB partition

For GPT Disks:

set id=de94bba4-06d1-4d40-a16a-bfd50179d6ac
gpt attributes=0x8000000000000001

For MBR Disks:

set id=27

exit

6. Re-enable Recovery Environment

reagentc /enable

🧠 Notes

  • Always back up before modifying partitions.
  • Do not assign a drive letter to the new recovery partition.
  • Works on Windows Server 2016, 2019, 2022 and Windows 10/11.
  • Source : https://thedxt.ca/2023/06/moving-windows-recovery-partition-correctly/