OpenBSD. The HDD had been used as an internal OS bootable drive. Worked fine. Now the intention is to make it an external USB bootable drive (for the reason of switching to another, fanless computer which happens to be a thin client and has no space inside for a HDD) No changes to HDD software installation have been made. The HDD has been put into a USB interface enclosure. It doesn't boot via USB. Neither on fanless thin client nor on the original machine where it booted fine being an internal drive. There is full disk encryption on the HDD. I checked USB boot with live OS image on my machines - they boot. I checked the USB-HDD - on already booted system [bioctl and mount](https://alextsang.net/articles/20170422-192400/index.html) and data is accessible. I tried playing with pertinent BIOS settings like AHCI and legacy boot. I don't say I've tried all combinations exhaustively as I'm not sure what to look at. Original machine where HDD had been internal. External attempt: [URL=https://i.imgur.com/2jRagPV.jpeg][IMG]https://i.imgur.com/2jRagPVh.jpeg[/IMG][/URL] Target machine - fanless thin client: It can see it: [URL=https://i.imgur.com/Di572Ht.jpeg][IMG]https://i.imgur.com/Di572Hth.jpeg[/IMG][/URL] But can't boot: [URL=https://i.imgur.com/uXdUtVB.jpeg][IMG]https://i.imgur.com/uXdUtVBh.jpeg[/IMG][/URL] I thought there should be no difference whether the drive is internal or via USB... Am I wrong? Is internal OS HDD bootable when connected as an external USB OS HDD? How do I?

Internal OS HDD -> external OS HDD = can't boot

uxer

OpenBSD.
The HDD had been used as an internal OS bootable drive. Worked fine.
Now the intention is to make it an external USB bootable drive
(for the reason of switching to another, fanless computer which happens to be a thin client and has no space inside for a HDD)
No changes to HDD software installation have been made. The HDD has been put into a USB interface enclosure.

It doesn't boot via USB.
Neither on fanless thin client nor on the original machine where it booted fine being an internal drive.

There is full disk encryption on the HDD.

I checked USB boot with live OS image on my machines - they boot.
I checked the USB-HDD - on already booted system bioctl and mount and data is accessible.
I tried playing with pertinent BIOS settings like AHCI and legacy boot. I don't say I've tried all combinations exhaustively as I'm not sure what to look at.

Original machine where HDD had been internal. External attempt:

Target machine - fanless thin client:
It can see it:

But can't boot:

I thought there should be no difference whether the drive is internal or via USB... Am I wrong?
Is internal OS HDD bootable when connected as an external USB OS HDD?
How do I?

rvp

uxer The Non-System disk or disk error means that the MBR doesn't have a valid boot-signature (0x55AA as the last bytes in the 1st sector), I think. Booting in legacy (ie. non-UEFI) mode requires a valid MBR + partition table with one of the partitions marked active.

I suggest that you try UEFI booting. Some UEFI-capable BIOSes allow booting off external HDDs (but, others don't--only external USB flash drives work on these). In these BIOSes, you can select the EFI ESP partition and bootloader file to use (you'll need an EFI ESP partition with the *.EFI files from here).

uxer

rvp Some UEFI-capable BIOSes allow booting off external HDDs (but, others don't--only external USB flash drives work on these)

How interesting. I thought "universal" in USB actually means "universal" - my mistake 🙂
"Universal" be like:

MBR doesn't have a valid boot-signature

I forgot to mention that the HDD in question is 4TB in capacity whereas MBR can up to 2TB. OpenBSD handles it fine reading MBR to boot and then reading disklabel partitions to access data IIUIC.
But can larger than MBR size affect BIOS/UEFI boot in this case?

rvp In these BIOSes, you can select the EFI ESP partition and bootloader file to use (you'll need an EFI ESP partition with the *.EFI files from here).

I'm new to it.
IIUIC, for this to work, I should have partitioned and installed in a certain way with *.EFI files.
Is this the correct certain way?
Having not done it in certain way means it won't work. Right?
Or *.EFI files can be added as an afterthought?
For now, it shows no options under EFI Boot - blue photo - #2

rvp

uxer But can larger than MBR size affect BIOS/UEFI boot in this case?

As long as the secondary bootstrap (if present) is within 2TB, the BIOS should have no problem loading it. After that it's up to the OS to cope.

uxer IIUIC, for this to work, I should have partitioned and installed in a certain way with *.EFI files.
Is this the correct certain way?

Yup. But, on reflection, you don't need to converto to GPT. It's possible to get both legacy BIOS and UEFI to boot using just MBR partitioning. You can see how this is done if you see how the OpenBSD USB install image is laid out which is as follows:

$ sudo fdisk /dev/sda

Welcome to fdisk (util-linux 2.39.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): p
Disk /dev/sda: 124 MiB, 130021888 bytes, 253949 sectors
Disk model: Flash Drive     
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device     Boot Start   End Sectors  Size Id Type
/dev/sda1          64  1023     960  480K ef EFI (FAT-12/16/32)
/dev/sda4  *     1024 11391   10368  5.1M a6 OpenBSD

Command (m for help): q

$

You make 2 partitions:

one a FAT with ID 0xEF which contains the \EFI\BOOT\*.EFI UEFI bootloader files.
another with ID 0xA6 which is the OpenBSD partition (further subdivided using a disklabel).

After that you install the bootstrap code using installboot for legacy BIOS booting. UEFI BIOSes will just load the appropriate \EFI\BOOT\*.EFI file from the EFI partition.

Can you see if installing the primary and secondary bootstraps on the disk using installboot gets you over the Non-system disk or disk error? You could do this using the OpenBSD USB install image, but, try booting off the same drive and running the command first.

If that doesn't work, can you show the output of these commands at the bootloader prompt?

boot> machine diskinfo
boot> set

Also the output of:

fdisk sd0                  # use correct disk for `sd0'
disklabel sd0              #            "

Let's see if / is the `a' partition in the disklabel (it usually is).

nandi78

I made my external hdd boot Openbsd with a live linux image started gparted removed the boot flag from the hdd uefi partition created an another uefi on the usb hdd and switched esp and the boot flag on and thats it i leave rhe boot flag off on the internal hdd.
It works perfectly