I'm not sure what type of drive you installed to but:
If you can, you might want to boot from a USB drive. Cloning a USB drive, for backup, is truly easy.
I don't know if you've tried the DVD as the ISO source, installing to a USB boot drive, route. If you haven't, it's worth a try.
Yes, that's exactly what i did - installed it from a DVD as ISO source, to the boot USB. This was the only way that worked 
Thnaks again
I’d also check to see if there is a bios update for the system. Systems like hp and dell heavily customize their bios and it is not uncommon for these customizations to change behavior that then gets “fixed” in subsequent bios updates.
Tried that, but it only offered me to rollback from 2.50 to 2.49.
Have you tried "enable" legacy support?
Jesus Christ, it boots! Thank for the help crashtest !
The correct combination for me was this:
Clear all BIOS settings, then SecureBoot Disabled-Legacy Enabled
disconnect all drives except one
Install OMV7 from DVD drive
reconnect back the drives
One thing was different this time is that i got a screen asking where to install the GRUB loader. Selected the only drive.
Now i have one minor problem - it boots ok everytime with 3,5' HDD's and an nvme, but when i connect my second USB flash drive, it boot-loops on the HP screen. Not sure why, but just gonna ignore that for now...
Thanks again
Also, where there are issues with using the standard ISO install, we've found that installing Debian's netinst first, then installing OMV by script may work in some instances.
-> Alt 64bit install.
OK so i've tried the Debian method (USB-to-USB).
The first time i accidentally installed debian with Gnome, and it booted after restart straight away just fine. But i went ahead and redid the whole installation again, according to the guide (and deselected Gnome).
And it didn't boot this time. But it boots fine when i manually go to grubx64.efi. This time it had 4 efi's - mmx64, shimx64, grubx64, something else.... But the damn BIOS does something to the boot, grub, or efi, i don't know.
Had enough for today, goodnight. (Probably will try again around january... 
)
Tried the CD/DVD method (went through four electronics stores to find a DVD ), sadly it's not booting.
I have found this guide, where it explains how to overwrite the grub configuration file:
So i booted into OMV with the manual grubx64.efi method. Logged in remotelythrough SSH with root. I was going to follow the tutorial from the step nr. 19, since i know my usb drive is "sda":
19 Use following command to open grub configuration file
sudo nano /boot/grub/grub.cfg
20 Find all lines with “linux /boot/vmlinuz……… /dev/sdxx”, change all “/dev/sdxx” to correct one, which is the one we have noted down from step 10, be careful do not touch anything else, or we will not be able to boot into the system
21 Once done, use Ctrl + X key combination to Exit the program, when asked, Press Y, then press Enter key.
In short, to Exit and save the file, Ctrl + x, Y, Enter
22 Now we need to update the grub with following command
sudo update-grub
23 We are done!But all i see in the grub file is something more like:
linux /boot/vmlinuz-6.1.0-15-amd64 root=UUID=465e522f-a8d3-4ba1-83a3-192b6fb7013e ro quietSo i don't know where to write the /dev/sda2/ part 
By chance, do you have a CD/DVD drive that will connect by USB? If so, burn the install ISO to a CD or DVD, boot on it, and install to the USB drive.
Hi, thanks for the idea. I do, actually have an external DVD drive. But will it help in any way? Because the OMV7 installer USB loads fine.... And installation finishes without any errors.
Anyway, i will try that!
OK, so i've tried manually copying the EFI boot file to BIOS. Found this thread, specifically comment nr. 6.
What i did:
efibootmgr -c -d /dev/sdb -p 1 -l \\efi\\debian\\grubx64.efi -L omv4. Got all the boot devices listed immediately , including the new "omv" entry.
5. Restart - still doesn't boot....
Funny enough, i can hit F9 and select the "grubx64.efi" file manually, and then it loads
Probably buying an HP computer was a mistake.
Hi everyone,
TL;DR can't boot OMV7 from USB, even though it installs without any errors. Tried all combinations in BIOS, different ports, different flash drives, resizing OMV partition, fixing GRUB. Only way i can boot it is from "Boot file" entry in HP boot menu. Then it loads fine. Any ideas what i could try next?
Background
So i've decided to build a DIY nas/homelab, bought a used sff pc - HP EliteDesk 800 g3 SFF, i5 7th gen, 32 gb RAM. Two 2TB IronWolf's, 256gb WD m.2 nvme, 32gb SanDisk flash drive.
Initially wanted to install OMV on the nvme, but didn't want to mess with partitioning, so i went with a new Sandisk 32gb USB. Leaving the nvme for docker containers and other "moving" parts.
The process
I've also found this tutorial - https://dcandy.wordpress.com/2…ls-to-install-bootloader/
but i didn't get any GRUB errors during installation...
So i don't know what to try next. Spent a few days trying to resolve this. Can it be a GRUB problem? BIOS? Should i try Debian install? Try another flash drive? The crazy part is that it boots sometimes, right after the install, or with the "boot from file" entry.
Maybe you have some ideas, thank you
Thanks for your opinion! I was kinda leaning towards option 3 myself
But are there any tradeoffs to having data and containers separated from main system? I mean, do you have to redirect the directories or something?
And using option nr 3, should i have several partitions on the SSD or just one?
Thanks 
Hi everyone,
my first post here! First of all, would like to thank the developer for the fine piece of software that OMV is
I would like to build my first NAS device from an old laptop that i was given - an HP G6 with 6GB of RAM and an Core i5. Thinking about buying a 2,5' SSD and a 2,5' HDD. Will do a DIY enclosure for the motherboard, but that's a different story.
Today i would like to ask you about how to properly distribute the duties between the hard drives. I am planning to install Plex docker container, and some torrenting apps. Will use the NAS only for media. As i understand, several different places need to exist on the system - OMV boot drive/partition, a drive for media, swap disk, plex metadata, plex transcoding, Docker container and plugins. The motherboard has two SATA conections, SD card reader, and plenty of USBs. What do you think would be the best way to go:
Haven't bought any SSD or HDD yet. I imagine i would need to have separate partitions for the different duties? Or i just install OMV and dockers and everything else on one single drive? By the way, been looking for this sort of info on the Plex forums, but there is nothing of this sort.
If you have some more patience, then a second question: What do you think, would i be able to install OMV to a SD/USB/SSD from another computer, then stick it into this PC and boot?
I've been having difficulties booting anything on this motherboard, mainly because the screen is missing, the BIOS is not outputting any video signal over HDMI, and i can't see what's going on on the screen. I believe there are some SecureBoot thingies going on in there. I only managed to boot Ubuntu from a CD ONCE, with some key combo, but didn't have any more luck since then. The old HDD with Windows is broken.
Any answers would be highly appreciated!
thanks in advance, your dude Paul