Partition disks during Windows setup

What you will achieve

Partition your system disk correctly during Windows setup — EFI System Partition, MSR, Windows volume, and optional recovery — without breaking boot or wiping secondary data drives.

1) Identify disks in the installer

1. Boot from Windows installation USB and choose Custom: Install Windows only (advanced).
2. Each physical disk appears by number and total size. If unsure which is which, disconnect secondary drives temporarily.
3. UEFI installs need GPT. On a blank GPT disk, selecting unallocated space lets setup create required partitions automatically.

2) Clean install on empty space

1. Select existing Windows partitions on the target disk, click Delete until you see Unallocated space on that disk only.
2. Click the unallocated space and choose New. Accept the size Windows suggests — it reserves space for recovery and the EFI partition.
3. Select the largest Primary partition and click Next to begin copying files.

3) Manual partitioning with diskpart (advanced)

From the installer, press Shift + F10 to open Command Prompt. Use only if you need a custom layout:

diskpart
list disk
select disk 0
clean
convert gpt
create partition efi size=260
format quick fs=fat32 label="System"
create partition msr size=16
create partition primary
format quick fs=ntfs label="Windows"
exit

4) Protect secondary data drives

1. Extra disks (D:, second NVMe) should remain untouched unless you intend to wipe them.
2. After install, open Disk Management (diskmgmt.msc) to assign drive letters to unused partitions.
3. Verify the EFI partition: in Disk Management it appears as EFI System Partition, usually without a drive letter.

5) BitLocker and encrypted disks

1. If BitLocker is enabled, suspend protection before partitioning: Control Panel → BitLocker → Suspend protection.
2. Setup may refuse to modify encrypted volumes without suspension or recovery key.
3. Re-enable BitLocker after successful install if you suspended it.

6) Extend C: after install

1. If unallocated space sits immediately after C: on the same disk, extend in diskmgmt.msc without third-party tools.
2. Non-contiguous unallocated space requires shrinking/moving partitions — backup first.

7) Windows Setup error messages

1. "Selected disk has an MBR partition table" on UEFI PC — delete all partitions and convert to GPT, or enable CSM/Legacy in firmware for MBR install (not for Windows 11).
2. "Windows cannot be installed to this disk. The partition is of an unrecognized type" — remove OEM recovery partitions only if you have USB recovery media elsewhere.
3. 0x80300024 often means no usable partition selected — click New on unallocated space first.

Related guides

• UEFI vs legacy BIOS boot explained
• Install Windows with a local account