Booting Windows 10 from external hard disk

Greetings.

I have a laptop (Predator Helios 300) with Windows 10 (Home, upgraded to Pro with Win7 key) installation that I like to keep clean. From time to time I will have to find a new piece of software for certain task. Normally I would start by trying out programs from various vendors to see which one suits me best. This requires me to install each program, try it out for a while and then uninstall it, if I don't like it. I would like to avoid doing this on my main OS, so, I thought I'd create a disposable Win10 installation on an external disk and boot into it whenever I plan to test new stuff.

The problem is I can't seem to be able to pull this off. I tried installing Win10 (I think it's build 20.04) from a bootable USB installation key that I made with the media creation tool. The target was an HDD in a docking station connected over USB, but the installer refused to install. Said something like windows can't be installed on disks connected over USB or firewire(?) interfaces. Next I connected this 2.5" disk over the internal SATA interface (removed current disk) and retried the installation. The system installed normally, booted normally and fully updated itself. Then I removed the disk, placed it back into the docking station and tried to boot from it. It started to boot fine because I saw the small animated orbiting dots icon, but then the machine suddenly rebooted. Afterwards it started to boot again and rebooted again until the PC repair showed up. It failed to fix anything and the system just booted and rebooted over and over again.

What's the proper way to install/boot a fully functional Windows 10 from an external disk i.e. without Windows2Go? I swear I was able to do it in the past when I cloned my older installation onto a 3,5" disk and I was able to boot from it fine from a docking station. No idea why it doesn't work this time. Disabling FastBoot didn't seem to do anything.

Ideas?

Assuming you have a UEFI computer - although it really doesn't make much difference, you have to manually create a system partition on the external usb drive, create a partition to hold the OS. Then manually apply the proper Windows 10 image to the OS partition. Then use the BCDBOOT command to write the boot files to the system partition you created. Here is a sample command sequence that will work on either UEFI or legacy BIOS computer. My Windows 10 installation ISO file is mounted as E: drive. It would be the same if using a Windows 10 USB flash drive that was E: drive.

Code:

diskpart
list disk
select disk # <-replace # with the actual number for the USB HDD in the docking station
clean <- this will erase the disk selected above, make sure you select the correct disk!
convert mbr
create part pri size=100
active
format fs=fat32 quick
assign letter=w
create part pri
format fs=ntfs quick
assign letter=t
exit
dism /Apply-Image /ImageFile:E:\Sources\install.esd /Index:1 /ApplyDir:T:\
bcdboot T:\Windows /s W: /f ALL
exit

Reboot the computer from the HDD in the docking station

Samuria said:

Simple way is to use free virtual box and create virtual machine very simple

Very good point! The OP also stated they upgraded to Windows 10 Pro, so they also have Hyper-V VM available.

NavyLCDR said:

Assuming you have a UEFI computer - although it really doesn't make much difference, you have to manually create a system partition on the external usb drive, create a partition to hold the OS. Then manually apply the proper Windows 10 image to the OS partition.

Yes, it's UEFI.

So, hypothetically speaking, what is the difference between this kind of installation and installation on a SATA-connected drive like the one I performed? Or rather, can I do anything to fix my existing installation and make it bootable?

I still wonder why my previous installation was able to boot fine this way. Could it be the fact that it used a custom bootloader that came along with system partition encryption using VeraCrypt?

I'd like to avoid using VM on my main OS (SSD).

It could be the change in the drive controller that occurs when you move it from a SATA port to the docking station.

NavyLCDR said:

Code:

diskpart
list disk
select disk # <-replace # with the actual number for the USB HDD in the docking station
clean <- this will erase the disk selected above, make sure you select the correct disk!
convert mbr
create part pri size=100
active
format fs=fat32 quick
assign letter=w
create part pri
format fs=ntfs quick
assign letter=t
exit
dism /Apply-Image /ImageFile:E:\Sources\install.esd /Index:1 /ApplyDir:T:\
bcdboot T:\Windows /s W: /f ALL
exit

Thanks. I've finally had some time to try this and it works perfectly.