Thursday 17 July 2014

Booting Windows8.1ToGo from a 'Removable-type' of USB Flash drive

I was recently contacted by 'JFL' about getting Windows8ToGo working on his 64GB SanDisk Extreme flash drive.

He was using Windows 8.1 Enterprise as the source and was following my earlier blog here.

The problem was that although he could install Windows OK, it would not boot.

His SanDisk Extreme was listed as being of the Removable type in RMPrepUSB and it was suspected that this may have been the problem because I found some comments from madscye and creosotechris here which sounded suspiciously like something has changed in Win8.1!

Now, in the past, I have had Win7ToGo booting from a USB removable flash drive OK many times. I have also booted Win 8 in the past on a removable USB Flash drive and that had worked OK.

Experiment 1
I already had a  21GB Win8.1ToGo.imgPTN file which I made earlier on my E2B USB HDD and I copied that onto my 32GB USB 3.0 Corsair GT E2B Removable-type drive (after deleting some ISOs to make room!).
I switched partitions using E2B and then I ran BCDBOOT on it to set the BCD correctly to boot from the different drive.
Result: it booted fine under VBox (which treats the USB drive as an HDD) but NOT on my Acer laptop (ever-lasting spinning circle of dots!).

So I did another experiment...

Experiment 2 - fresh install
1. Using DISM, Install Win8.1 Enterprise onto a 16Gb Lexar JumpDrive USB 2.0 which appears as a Fixed Disk (install took about an hour!)
2. Boot from the Lexar USB drive on an Acer Aspire 7741G laptop - go through user setup to Desktop (again very slow!).
3. Reboot and check boots from USB drive OK - all was working fine.
4. Use Bootit.exe to Flip the Bit so the USB drive is now a Removable drive
5. Boot from it on the Acer laptop again
Result: FAIL! (ever-lasting spinning circle of dots)

Experiment 3
1. I re-ran BootIt.exe and flipped back to a Fixed Disk type again
Result: The Lexar boots just fine!

So proof that Win 8.1 ToGo must be run from a Fixed-disk type of  USB drive!

[Update] Win10 (first release) also has same issue. It can be overcome by booting from a VHD file containing WindowsToGo.
Windows 10 Creator now allows us to use Removable or Fixed disk USB drives for flat-file booting - hurrah!
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