[SOLVED] GRUB installation on a USB device


Well-Known Member
Feb 13, 2019
I have a PVE project where I am installing 6.0 on a HP Microserver Gen8. Unfortunately this machine can only boot from the first HDD (in AHCI mode) and I would like to keep the big drives for storage (ceph).

Additionally, the server does not have have UEFI and can only boot from the USB 2.0 ports, USB 3.0 works only after the OS takes over. I have tried installing pve on a connected to a 2.0 port, but it is very slow. So I was thinking use the pve installation connected to a 3.0 port and install a second usb key connected to a 2.0 port only with grub pointing to /dev/mapper/pve-root.

I tried using the Debian Live image and the Boot Repair Disk (https://sourceforge.net/p/boot-repair-cd/home/Home/) image to boot into and install grub, without success. With the Boot Repair Disk, I get stuck on the lack of EFI, even though I disable all EFI settings I could find, the tool complains that I have booted in legacy mode with a gpt device and that I should reboot in UEFI mode (which the server is not capable of).

Instead of using these tools, are there perhaps any grub gurus able to help with a well phrased grub-install command?
So , for anyone else with a similar situation, I solved it by
  1. booting into my pve installation (on usb 2)
  2. inserting the boot usb and copying the /boot folder to the root of the boot usb
  3. running grub-install /dev/sdX (the boot usb device)
It ended up still being excruciatingly slow so I gave up and installed pve on a ssd partition on, still having to use the boot usb to boot as the HP microserver is very limited in selecting boot devices.


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