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Missing OS on reconnected drive

Ask for help with issues regarding the Installations of the Debian O/S.
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mdm55
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Missing OS on reconnected drive

#1 Post by mdm55 »

I have a P8C-WS (Xeon E3-1275 and Intel C216 chipset) with a number of drives that are connected to the power supply with DPDT switches so that they can be electrically isolated, including two boot drives that I can toggle between two operating systems. I installed Debian 11 on one of the boot drives using the default installer partition scheme and was able to reboot the machine a number of times as I added drivers. After switching over to the other boot drive (Windows 7) and returning to the Debian installation, I receive a "Missing OS" message. This was repeated a couple of times. As a test before coming here to ask for help I installed Intel Clear Linux in place of Debian and was able to boot Clear Linux after toggling back from the Windows 7 boot drive. Since the Clear LInux and Windows 7 installations can be toggled without a problem it seems that Debian should work as well. What configuration changes do I need in order to keep from losing the OS after toggling back from the other boot drive? My best guess is that there is some interaction between the UEFI BIOS and GRUB. I have been using Debian on an Intel NUC box for a while and I would like to stay with it as I convert other machines to Linux.

TIA
Dean

p.H
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Re: Missing OS on reconnected drive

#2 Post by p.H »

Did you install Debian in UEFI or BIOS/legacy mode ?
If UEFI, did you install GRUB in the removable device path (available only in expert install or with dpkg-reconfigure grub-efi-<arch>) ?
If not, did you check whether the "debian" EFI boot entry was still present after toggling the drive ?

The Debian default is to not install GRUB in the removable device path and rely only on the EFI boot entry to boot. However I have seen at least one UEFI firmware which deletes EFI boot entries if the associated drive/partition/pathname is missing.

PS : you should consider adding line breaks in your posts.

mdm55
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Joined: 2021-03-07 23:05

Re: Missing OS on reconnected drive

#3 Post by mdm55 »

Did you install Debian in UEFI or BIOS/legacy mode ?
If UEFI, did you install GRUB in the removable device path (available only in expert install or with dpkg-reconfigure grub-efi-<arch>) ?

When I selected UEFI boot and legacy boot for the USB device (debian-live-11.0.0-amd64-cinnamon.iso) I got two different installer screens, but neither indicated UEFI. In all cases I have used the graphical installer and accepted the defaults.

If not, did you check whether the "debian" EFI boot entry was still present after toggling the drive ?

i could not find the expected /boot/efi/EFI/debian directory after booting from the LiveUSB. Gparted showed that the boot partition was unreadable
(see attached image)

Screenshot from 2021-09-02 20-23-50.png
Screenshot from 2021-09-02 20-23-50.png (228.81 KiB) Viewed 2464 times

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Re: Missing OS on reconnected drive

#4 Post by p.H »

Please quote properly, with "quote" tags. Like this :
mdm55 wrote: 2021-09-02 20:52 i could not find the expected /boot/efi/EFI/debian directory after booting from the LiveUSB.
How did you search ? This path is valid only when the EFI partition is mounted on /boot/efi.
mdm55 wrote: 2021-09-02 20:52 Gparted showed that the boot partition was unreadable
No. Gparted told you that it could not examine the partition contents due to missing (indicated) software.
What are you using Gparted for ? It is a partition table editor. You do not want to edit the partition table.
If you want to see a partition contents, just mount it and browse it.

Anyway, EFI boot entries are stored in the motherboard's NVRAM, not in the EFI partition. You can list them with efibootmgr.
In the EFI partition you can check if GRUB was installed in the removable path (EFI/Boot/)

mdm55
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Re: Missing OS on reconnected drive

#5 Post by mdm55 »

How did you search ? This path is valid only when the EFI partition is mounted on /boot/efi.
How did you search ? This path is valid only when the EFI partition is mounted on /boot/efi
I opened the File Manager as root and saw that there were no sub-directories for /boot/efi, that is why I went to gparted. I had copied /EFI to another device and tried replacing it but it did not help. I had already used efibootmgr to determine the boot entry path. After toggling, efibootmgr showed that the debian boot entry and /EFI was missing as well. My most recent attempt was to use the standard installer instead of Live and to install in a single partition. That did not help. The message I get now is:

Missing OS

GRUB

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Re: Missing OS on reconnected drive

#6 Post by p.H »

mdm55 wrote: 2021-09-03 00:30 I opened the File Manager as root and saw that there were no sub-directories for /boot/efi
Do you mean "no sub-directory /boot/efi (in /boot)" or "no sub-directory in /boot/efi" ?
The latter is normal : /boot/efi is just a mount point for the EFI partition and should be empty when the partition is not mounted on it. The /boot/efi/EFI subdirectory is present only when the EFI partition is mounted on /boot/efi. Did you mount the EFI partition somewhere ?
mdm55 wrote: 2021-09-03 00:30 efibootmgr showed that the debian boot entry and /EFI was missing as well.
efibootmgr does not show on-disk directories, only in-NVRAM EFI boot entries. The missing EFI boot entry "debian" explains why the firmware cannot find any bootable OS. You must install GRUB in the removable device path to avoid this. Here are three possible ways to do it, preferred first :

Code: Select all

dpkg-reconfigure grub-efi-amd64 # or grub-efi-ia32 if you have a 32 bit UEFI implementation

Code: Select all

grub-install --force-extra-removable
copy EFI/debian/grubx64.efi into EFI/Boot/
copy EFI/debian/shimx64.efi as EFI/Boot/Bootx64.efi
unlike the previous ones, can be done from another system without chroot

mdm55
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Re: Missing OS on reconnected drive

#7 Post by mdm55 »

Thanks for your efforts.

A couple of months ago I tried to install a PCIe SATA controller on the P8C-WS and Windows 7 would not boot from an existing drive when the card was installed. I learned that at some point Asus had added a CSM to the BIOS but there was no documentation available. Neither the card manufacturer nor several people at Asus could provide any information about the CSM settings. With regard to the current problem, I changed the settings on the CSM, at one point making Windows 7 unbootable. After further changes to the settings I was able to boot Windows 7 and I once again installed Debian. This install must have been a true legacy install since there were steps involving GRUB that I had not seen before. Clear Linux was probably able to boot as it had been installed in legacy mode.

After reading the following discourse I realize that dual boot is probably an intermediate step to ultimately running Windows 7 subordinate to Linux in a virtual machine on a Supermicro motherboard.

https://www.happyassassin.net/posts/201 ... work-then/

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Re: Missing OS on reconnected drive

#8 Post by p.H »

Now you got me lost. If you want to know how exactly Debian in installed and is supposed to boot, launch a live system which includes bootinfoscript or install it, run it and post the report.

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