Windows HVM Restore - Inaccessible Boot Device

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Aug 9, 2022, 2:44:14 PMAug 9
to qubes-users
Hi folks,

I had a catastrophic failure with my Librem 14v1 and am currently trying to get everything back up and running from my latest backup onto a new machine (Dell Precision 7510), pending the return of my repaired Librem.

My Linux App VMs all seem good, but my Windows HVM is failing to start with "Inaccessible Boot Device".  The steps I would normally take to attempt to troubleshoot a Windows machine in this state aren't working (booting from the Windows Install Media and/or some kind of PE disc).  The VM just shuts down before either come up.  Windows automatic repair fails because there's no local local admin account.

The HVM was originally created from a Hyper-V VM whose disk was converted to qcow2 and then imported to Qubes.  It's functioned fine on my original machine since.  Backup and restore was done via the standard GUI tools within Qubes.

One thing I've never been clear on is where the disks live once they're in Qubes.  I know it's something to do with lvm, but I'm unsure how to access them or re-export them for use in another hypervisor.

I have access to both the recent backup I took and the disk out of the bad laptop.  Any tips would be much appreciated.  Thanks!


Aug 9, 2022, 6:10:22 PMAug 9
to qubes-users
Update: I was able to restore my backup to a Qubes 4.0 system and it worked.  The new system is 4.1...  That gives me something else to chase down.


Aug 10, 2022, 3:55:59 PMAug 10
to qubes-users

Closing the loop on this for anyone in the future.  In the end, I had to:
From the working 4.0 host:
- Enable a local admin + login one time.
- Take a fresh backup.
On the target 4.1 host:
- Restore the backup
- in a dom0 terminal, run "qvm-prefs <VM Name> qrexec_timeout 60000000" <---- number is just a large, arbitrary number so Qubes doesn't shut the machine down when qrexec doesn't come up.
- Boot the machine 3x times.  On the third time, Automatic Repair starts.
- Logged in with the local admin.
- Attempted automatic repair - no good.
- Opened a command prompt and used diskpart to assign the boot partition to letter S and the Windows partition to letter C.
- used bcdboot to regenerate the boot files.
- used bcdedit to ensure the correct partition was set.
- reboot

This *still* failed on the next boot, however I was able to get into Windows Safe Mode.  Another reboot had me functioning normally.
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