Installing NixOS on a system without EFI and the bootloader on a different hard disk

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1

I got a small server from HP (Proliant Gen8). The installation preconditions are a bit special:

It has 5 SATA ports (4 for the drive bays and one for a optical drive) but the BIOS (no EFI) can’t boot from the optical drive for some reason. However, there’s an internal SD-Card reader which can be used for boot. I don’t want to install the whole OS on the SD-Card for obvious reasons but just writing the bootloader should be fine. I don’t want to write the bootloader on any of the other SATA disks because they should be dedicated to storage.

Considering these conditions I came up with following configuration for the NixOS installation (only the boot part):

{ config, pkgs, ... }:

{
  imports =
    [ # Include the results of the hardware scan.
      ./hardware-configuration.nix
    ];

  boot.loader.grub.enable = true;
  boot.loader.grub.version = 2;
  boot.loader.grub.devices = [
    "/dev/disk/by-id/usb-HP_iLO_Internal_SD-CARD_000002660A01-0:0"
  ];

  boot.initrd = {
    luks.devices = [
      {
        name = "root";
        device = "/dev/disk/by-uuid/94796159-5d55-417c-bdda-e9d482e19c71";
        preLVM = true;
        allowDiscards = true;
      }
    ];
  };
  fileSystems."/".options = [ "noatime" "nodiratime" ];

The installation works fine but after a reboot, the BIOS can’t detect any bootable system. For the whole installation I followed this guide but without the EFI part: Installation of NixOS with encrypted root · GitHub

2

Have you installed anything from SD card before?

3

Yes I already installed CentOS 4 years ago using by using the SD-Card for the bootloader. But I can’t remember how I did it exactly and I’m not experienced with NixOS yet.

4

How do you currently boot into the Nix installer? (If you’re using a bootable media at all?)

5

I use a USB storage which I set as temporary boot media in the BIOS.

6

I’d start by verifying if the sd card can be used for boot at all. Try to copy installation media on the sd card first? Your config seems fine

7

I have a dl380 g7 myself, and while most folks install esxi on the sdcard, I also choose not to use it. Mostly due to having to keep the nix store in the root and to date I never had a sdcard that lasted very long. I use one of the SAS disks to boot the beast, and my nix configuration is straightforward.

8

Update for the sake of documentation: The partition on the SD card was not marked as bootable. You have to do this manually. For some reason I thought the NixOS install would do that for me or would at least warn me if I try to install Grub on a non-bootable partition.

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