I'm new to OMV, but have been using various flavors of linux for a few decades now. I've been going through the process of transitioning my Asustor 5004T NAS to both new drives and transitioning to OMV.
I have an external USB SSD that I am using as the boot drive.
Background
Under the Asustor OS I had 4x5TB drives in RAID. I copied all my data to one of my new 18TB WD Red Pro's in an external USB case.
I then removed 3 of the 5TB from the NAS and exchanged them for the new 18TB drives. This gave me 1x5TB and 3x18TB inside the Asustor case.
I installed OMV to the USB SSD via a USB flash stick, and upon system boot the drive was recognized by the BIOS as bootable with the name "debian".
My first experience with OMV was attempting to update the system and install the Proxmox kernel. Several times attempting this I noticed that upon reboot/powercycle the USB SSD was no longer bootable, the BIOS was not seeing "debian".
I figured this could be due to the installation of the kernels and something not setting up grub properly. I finally got it to work by not updating the Debian kernel and just installing Proxmox. For the few days since this I had no issue powercycling/rebooting.
So I now felt comfortable setting up the new ZFS pool and moving my data over.
I created a raidz1 pool across the 3x18TB and 1x5TB, this gave me the same space I had previously with the intent of moving my data over, replacing the 5TB with the 18TB and then expanding. Last night all my data was finally rsync'd to the new zpool and I got all my services up and running. I then started the replace command and this morning my resilvering was completed and I had full access to the entire drive space according to ZFS! (very cool filesystem!)
I shut down the system with the poweroff command, pulled the 5TB drive from the case and put in the 18TB that had been on USB. Now all four 18TB drives are in the machine, and
the USB SSD the only USB drive connected. I powered up the system and ran into the same issue where the USB SSD is no longer bootable, and the BIOS is not seeing 'debian'.
Resolution
Digging into this I discovered that the EFI boot system is at issue. At this point the internet points you to efibootmgr to manage the EFI boot parameters of the system,
and while this worked, the changes appeared to be temporary, with the boot entry for the drive "disappearing" after powercycle. This eventually led me to discover that this is apparently a common issue with some firmware and that most people get it to work by fixing it in the UEFI shell with a command called bcfg. The Asustor bios provides a method to boot into the UEFI shell that comes with the system, however this version is too old and does not include bcfg. However, you can run any compatible UEFI shell from a USB drive.
I was able to find prebuilt shells at,
GitHub - pbatard/UEFI-Shell: UEFI Shell binary images, generated from EDK2 stable
Apparently these are bootable ISO, however I went an alternate route since my BIOS allows me to select a boot shell from a menu, so I copied the shell from the ISO to a FAT formatted USB drive and launched the shell that way via the BIOS.
Once in the bcfg command worked and I followed the directions I found on several useful websites,
Unified Extensible Firmware Interface - ArchWiki (archlinux.org)
HOWTO - Add UEFI Shell boot option | By: ErikW - Digital Storm Forums
UEFI Boot Option Management - BlueField DPU SW Manual 3.6.0.11699 - NVIDIA Networking Docs
So far this has worked through multiple boots, and I copied the prebuilt shell to my Debian Live USB drive for future use. Hopefully this can help others, if not just act as a place for all my findings if the issue continues to happen to me.
