Installing Ubuntu Server 26.04 on a Legacy HP Proliant Server Gen8

[rjd324]

Ubuntu Version

Ubuntu 26.04 LTS

Desktop Environment (if applicable)

None (server/headless)

Problem Description

Any numbered bullet point is an assertion or question.

1 - It is not the partition layout of a USB disk that determines whether it will boot into UEFI or BIOS mode but how the host machine is set up. For example, forcefully choosing BIOS mode in the BIOS options means that the host machine will attempt to boot in BIOS mode.
2 - UEFI is backward-compatible with MBR
3 - If I run DD on the Ubuntu Server image to a USB Flash Drive then that must create an MBR on the USB Flash Drive and hence bullet point 2 must be true - otherwise you would not be able to boot the Ubuntu Installer USB Flash Drive on machines that do not support UEFI.

After 10 years of continuous use, my G8 server’s NAND seems to be broken and I am unable to use the micro SD card slot anymore. It has given me the opportunity to finally update the OS on the G8 machine. I would like to install Ubuntu Server on the G8 machine. I used Ventoy and I am sure I chose MBR when uploading the Ubuntu Server IMG to the USB Flash Drive. I can boot into Ubuntu Server, but it seems to have booted into “UEFI” mode because the only option I have is to create a GPT partition. I have also tried getting into the shell and using FDISK to reset the device and set up an MBR table and an EXT4 partition. Still, the only option I see is for GPT.

4 - My Gen8 machine is booting into UEFI mode and that is why I can only see the option of a GPT partition.

wrt #4, I am a little confused. Apparently the Gen8 machine uses BIOS (the source of my information are just search engines), but something can somehow trick it into booting into UEFI mode?

It would be useful for someone to correct me. At this point in time, my goal is to be able to install Ubuntu Server on the SSD without using UEFI/GPT.

Regards.

Relevant System Information

HP Proliant server Gen8

[yancek]

You should have 2 options in the BIOS for the USB, something like USB HD and also USB UEFI and the former would boot in legacy/csm mode to install in MBR mode and the latter would boot and install in UEFI mode. Do you see such options in the BIOS?

You can install Ubuntu and other linux OS’s in legacy/MBR mode on a GPT disk if you create an unformatted 1MB partition with the flag set as bios-boot/bios_grub.

[rjd324]

Solved.

The G8 machine always boots using legacy mode. There is no UEFI. I ended up using Ubuntu version 20 (legacy) so that I could avoid using subiquity. Using the legacy version seems simpler to me.

The configuration in the G8 machine is 4 SATA drives as part of the RAID. I added an extra SSD drive to the internal SATA port which is really meant for optical drives. If SATA AHCI (non-legacy), port #5 (also known as ODD - optical drive) is being used for the SATA drive which I wanted to store the Operating System on. The issue is that in AHCI mode port #5 is not visible. Since my SD card slot is now broken, I put Ubuntu Server legacy version 20.04 onto a flash drive and plugged it into one of the external USB ports at the back. I then inserted a cheap flash drive in the internal port. The internal USB is then used as for MBR/GRUB2 and contains the /boot partition (which you configure during the Ubuntu Server setup). The / partition is then completely on the SSD drive.

Once version 20 was installed, it was a matter of upgrading twice to version 24. 26 is not yet available through do-release-upgrade.