convert mbr not needed after diskpart clean command?

Ztruker · 18 Mar 2019

@NavyLCDR, you said in another thread:

The clean command in diskpart automatically converts the drive to MBR. "Convert MBR" is never necessary after the "clean" command.

I tested this and does not appear to be the case. Flash drive is GPT before and after the clean command is run.

Code:

>diskpart

Microsoft DiskPart version 10.0.17763.1

Copyright (C) Microsoft Corporation.
On computer: DESKTOP

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          465 GB    46 GB        *
  Disk 1    Online         1863 GB  1024 KB        *
  Disk 2    Online         1863 GB      0 B        *
  Disk 3    No Media           0 B      0 B
  Disk 4    Online           14 GB      0 B        *

DISKPART> sel disk 4

Disk 4 is now the selected disk.

DISKPART> clean

DiskPart succeeded in cleaning the disk.

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          465 GB    46 GB        *
  Disk 1    Online         1863 GB  1024 KB        *
  Disk 2    Online         1863 GB      0 B        *
  Disk 3    No Media           0 B      0 B
* Disk 4    Online           14 GB    14 GB        *

My system is a Lenovo K450 4th gen i7 4770 Quad 3.4Ghz
UEFI, all drives are GPT.
1809 17763.379

convert mbr not needed after diskpart clean command?-image.png

Thoughts? Maybe the command needs to be clean all? If so, that would be a lot slower so the convert mbr would be better.

Clintlgm · 18 Mar 2019

The Diskpart Clean command should leave your Disk/SSD unused space RAW, as it came from the factory neither MBR nor GPT

zbook · 18 Mar 2019

See the lifespan warning in this link for running clean all on a SSD:
Disk - Clean and Clean All with Diskpart Command - Windows 7 Help Forums
Erase Disk using Diskpart Clean Command in Windows 10 | Tutorials

Bree · 18 Mar 2019

Clintlgm said:

The Diskpart Clean command should leave your Disk/SSD unused space RAW, as it came from the factory neither MBR nor GPT

That does not seem to be what @Brink's tutorial says. It seems that it overwrites all the information in the partition table, but leave the table as it found it (MBR or GPT).

The clean command removes any and all partition or volume formatting from the disk with focus. On master boot record (MBR) disks, only the MBR partitioning information and hidden sector information are overwritten. On GUID partition table (GPT) disks, the GPT partitioning information, including the Protective MBR, is overwritten; there is no hidden sector information.

Erase Disk using Diskpart Clean Command in Windows 10 | Tutorials

My experience agrees with @Ztruker, a usb flash drive with a gpt layout will still be gpt after using Diskpart Clean.

NavyLCDR · 18 Mar 2019

Then it must be true for USB HDD/SSDs only:

Code:

Microsoft Windows [Version 10.0.18358.1]
(c) 2019 Microsoft Corporation. All rights reserved.

C:\WINDOWS\system32>diskpart

Microsoft DiskPart version 10.0.18358.1

Copyright (C) Microsoft Corporation.
On computer: JOHN-LAPTOP

DISKPART> lis dis

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          476 GB      0 B        *
  Disk 1    Online          476 GB  2048 KB        *
  Disk 2    Online          298 GB      0 B        *

DISKPART> sel dis 2

Disk 2 is now the selected disk.

DISKPART> clean

DiskPart succeeded in cleaning the disk.

DISKPART> lis dis

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          476 GB      0 B        *
  Disk 1    Online          476 GB  2048 KB        *
* Disk 2    Online          298 GB   298 GB

DISKPART>

Not for flash drives. Although I can't honestly understand why you would want a GPT flash drive anyway. But I was mistaken about flash drives.

Bree · 18 Mar 2019

NavyLCDR said:

...I can't honestly understand why you would want a GPT flash drive anyway....

A lot get turned into gpt without the owner realising by using of Rufus

zbook · 18 Mar 2019

See this link for creating MBR after the clean command:
Change a GUID Partition Table (GPT) disk into a Master Boot Record (MBR) disk | Microsoft Docs

See option 4 in this link:
Convert GPT Disk to MBR Disk in Windows 10 | Tutorials

Ztruker · 19 Mar 2019

Bree said:

A lot get turned into gpt without the owner realising by using of Rufus

Yup, that's where that particular flash drive came from. I had used Rufus some time back to create it as UEFI/GPT.

Thanks all for chiming in on this.

Ztruker · 19 Mar 2019

zbook said:

See this link for creating MBR after the clean command:
Change a GUID Partition Table (GPT) disk into a Master Boot Record (MBR) disk | Microsoft Docs

See option 4 in this link:
Convert GPT Disk to MBR Disk in Windows 10 | Tutorials

@zbook, thanks. That is what started this thread though. The instructions I had posted included convert mbr after running the clean command and @NavyLCDR said it wasn't needed. I tested and it was needed so here we are.

Consensus is it's not need for hard drives but is needed for flash drives.

Clintlgm · 19 Mar 2019

Ztruker said:

@zbook, thanks. That is what started this thread though. The instructions I had posted included convert mbr after running the clean command and @NavyLCDR said it wasn't needed. I tested and it was needed so here we are.

Consensus is it's not need for hard drives but is needed for flash drives.

Well we all learned something on this thread, I had no Idea that a flash drive would be any different than a ssd