Create a bootable USB flash drive using Diskpart

  1. sportsfan148's Avatar
    Posts : 977
    Windows 10 Home 202H
       #1

    Create a bootable USB flash drive using Diskpart


    Hi, Its great to see the addition of Option 4 (Diskpart method) in the Create Bootable USB flash drive to install Windows 10 Tutorial .
    Create Bootable USB Flash Drive to Install Windows 10

    There's an extra command directly after the clean command, "convert mbr". Is this mandatory now to type in convert mbr?
    I always thought that when you use the clean command, it wipes off all data, formatting and also the partition table. The next command I type after clean is create partition primary which I thought also creates the mbr. Have I got that right?..or have I been making a mistake by not typing in convert mbr after the clean command?
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  2. Brink's Avatar
    Posts : 56,948
    64-bit Windows 10 Pro for Workstations build 21376
       #2

    Hello,

    The "convert mbr" command is there to just make sure it happens to prevent any possible issues.
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  3. sportsfan148's Avatar
    Posts : 977
    Windows 10 Home 202H
    Thread Starter
       #3

    Brink said:
    Hello,

    The "convert mbr" command is there to just make sure it happens to prevent any possible issues.
    Hi Shawn. So under normal circumstances the convert mbr command is optional and doesn't normally have to be used. Does the create partition primary command set it up as mbr anyway when it creates the partition..have I got that right?
    Last edited by sportsfan148; 27 Aug 2019 at 18:20.
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  4. Brink's Avatar
    Posts : 56,948
    64-bit Windows 10 Pro for Workstations build 21376
       #4

    I can't remember, but I would recommend to use the command to make sure.
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  5. NavyLCDR's Avatar
    Posts : 15,586
    Windows 10 Pro
       #5

    sportsfan148 said:
    Hi Shawn. So under normal circumstances the convert mbr command is optional and doesn't normally have to be used. Does the create partition primary command set it up as mbr anyway when it creates the partition..have I got that right?
    The create primary partition command will not change a GPT drive to MBR, nor will it change an MBR drive to GPT. It just creates a partition under whichever partition type the drive is set up for. Remember, partitions are neither MBR nor GPT. The physical drive itself is either MBR or GPT. MBR and GPT are just different methods of storing the information that defines the partitions on the physical drive.

    The reason the convert mbr command is there is to ensure universal compatibility. Legacy BIOS (or CSM mode) and UEFI can both boot MBR drives. However, a GPT drive can only be booted from UEFI.
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  6. sportsfan148's Avatar
    Posts : 977
    Windows 10 Home 202H
    Thread Starter
       #6

    NavyLCDR said:
    The create primary partition command will not change a GPT drive to MBR, nor will it change an MBR drive to GPT. It just creates a partition under whichever partition type the drive is set up for. Remember, partitions are neither MBR nor GPT. The physical drive itself is either MBR or GPT. MBR and GPT are just different methods of storing the information that defines the partitions on the physical drive.

    The reason the convert mbr command is there is to ensure universal compatibility. Legacy BIOS (or CSM mode) and UEFI can both boot MBR drives. However, a GPT drive can only be booted from UEFI.
    Hi mate. Thanks for clarifying things for me.
    Do you mind just giving me a bit more info on what exactly the Clean command does.
    Does it wipe the MBR partition table putting it back to its original state when the flash drive was purchased?
    Ive always thought that the Clean command wipes the MBR, and whatever the format is (NTFS or FAT32) removing all data from the drive giving you a totally blank flash drive. That is why I thought , after the Clean command, Create Partition Primary must be what puts the MBR back in a clean state on the drive along with the primary partition.
    Is it just that the Clean command removes all partitions. A flash drive is either MBR or GPT... Clean command does nothing at all to alter that but when you create partition primary the MBR just starts afresh?
    Im just trying to get a better understanding of the mechanics of how exactly it works.
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  7. NavyLCDR's Avatar
    Posts : 15,586
    Windows 10 Pro
       #7

    The clean command puts either the MBR or the GPT back to a clean state with no partitions defined. It erases the partition table. Unless you use the "clean all" command, all the previous data is actually still on the drive. The clean command by itself only erases the data that defined the partitions the data was stored in. The clean all command will actually go through and write 0's to the entire drive, not just the partition table.

    The create primary partition command does not create an MBR nor a GPT. It simply creates a entry in the existing MBR or GPT partition table to define a partition.
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  8. sportsfan148's Avatar
    Posts : 977
    Windows 10 Home 202H
    Thread Starter
       #8

    NavyLCDR said:
    The clean command puts either the MBR or the GPT back to a clean state with no partitions defined. It erases the partition table. Unless you use the "clean all" command, all the previous data is actually still on the drive. The clean command by itself only erases the data that defined the partitions the data was stored in. The clean all command will actually go through and write 0's to the entire drive, not just the partition table.

    The create primary partition command does not create an MBR nor a GPT. It simply creates a entry in the existing MBR or GPT partition table to define a partition.
    Thanks very much for the clear explanation. The Clean All command sounds exactly the same as a Full Format (writing zero's across the drive).
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