Solved what does turning the BootDeviceFlag to 0x14 really do when booting from a device plugged into a USB 3.0 port?


trinhanhduc

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Like the title said, I kept seeing others getting the inaccessible_boot_device error when installing windows on a removable media and the only fix to this issue is to change the value of BootDeviceFlags. What does this do and why am I still be able to boot Hirenboot cd pe and windows installer from a USB device plugged into a USB 3.0 port?
 

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Except for Windows To Go, Windows is not designed to run from a removable or network mounted device, because it can be unexpectedly disconnected from the system. You can force the BootDeviceFlag to have Windows ignore this restriction.

Windows ISO and the various USB repair tools boot from WinPE, which is designed to copy itself to a RAM disk in memory. So it doesn't care if you unexpectedly unplug the device after booting up. WinPE is a lightweight, stripped down version of Windows. A full Windows would get data consistency errors if you unplugged the storage device while it's running.
 
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Except for Windows To Go, Windows is not designed to run from a removable or network mounted device, because it can be unexpectedly disconnected from the system. You can force the BootDeviceFlag to have Windows ignore this restriction.

Windows ISO and the various USB repair tools boot from WinPE, which is designed to copy itself to a RAM disk in memory. So it doesn't care if you unexpectedly unplug the device after booting up. WinPE is a lightweight, stripped down version of Windows. A full Windows would get data consistency errors if you unplugged the storage device while it's running.
Then why don't I get the inaccessible boot device error when booting from USB 3.0 USB, I'm just curious
 

My Computer My Computer

At a glance

Windows 1011th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz8 GBytesIntel Iris Xe Graphics, NVIDIA GeForce MX330
OS
Windows 10
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Laptop
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DELL
CPU
11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
Motherboard
DELL 0NX5H3
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8 GBytes
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Intel Iris Xe Graphics, NVIDIA GeForce MX330
Screen Resolution
1920x1080
Hard Drives
PM991a NVMe Samsung 512GB
The Windows Installer, Windows PE, Hirens and other Boot disks are not the Microsoft Windows Operating Systems
The Windows OS is not designed to run from a USB drive unless you running Windows to Go
It would be far too slow running even at USB 3.3 speed
 

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