Hi! I'm also struggling with a Disko/ZFS issue.

I've set options.mountpoint = "legacy".
But when I nix eval the nixosConfiguration, I don't see legacy in the fileSystems attribute?
What am I doing wrong?

$ nix eval .#nixosConfigurations.nas-2024.config.disko.devices.zpool.nvmepool.datasets."root/nix".options
{ mountpoint = "legacy"; }

$ nix eval .#nixosConfigurations.nas-2024.config.disko.devices.zpool.nvmepool.datasets."root/nix".mountpoint
"/nix"

# on nas-2024 during emergency boot mode
$ zfs list nvmepool/root/nix
NAME                        USED  AVAIL  REFER  MOUNTPOINT
nvmepool/root/nix    XXX    YYY     ZZZ      /nix

My config matches AFAICT this post by ElvishJerrico: https://discourse.nixos.org/t/disko-and-zfs-emergency-mode-during-boot/58138/8

Hi! I'm also struggling with a Disko/ZFS issue.

I've set options.mountpoint = "legacy".
But when I zfs list the dataset, I don't see legacy in the datasets mountpoint attribute?
What am I doing wrong?

$ nix eval .#nixosConfigurations.nas-2024.config.disko.devices.zpool.nvmepool.datasets."root/nix".options
{ mountpoint = "legacy"; }

$ nix eval .#nixosConfigurations.nas-2024.config.disko.devices.zpool.nvmepool.datasets."root/nix".mountpoint
"/nix"

# on nas-2024 during emergency boot mode
$ zfs list nvmepool/root/nix
NAME                        USED  AVAIL  REFER  MOUNTPOINT
nvmepool/root/nix    XXX    YYY     ZZZ      /nix

My config matches AFAICT this post by ElvishJerrico: https://discourse.nixos.org/t/disko-and-zfs-emergency-mode-during-boot/58138/8

Couple of questions about NixOS live USBs:

I want to partition my 64 GB USB flash drive into two partitions (FAT32 live USB + ext4 storage), so I used the following disko config:

let
  usb = "/dev/disk/by-id/usb-USB_SanDisk_3.2Gen1_0401a943ae4197a38a6f9070194e9ea2b3fb8dbb7997e05ed1b197c0e28946be4b8f000000000000000000001cf4be6800926418a955810751ab6336-0:0";
in {
  disko.devices = {
    disk = {
      live = {
        type = "disk";
        device = usb;
        content = {
          type = "gpt";
          partitions = {
            ESP = {
              type = "EF00";
              device = "${usb}-part1";
              priority = 0;
              size = "8192M";
              content = {
                type = "filesystem";
                format = "vfat";
              };
            };
            storage = {
              device = "${usb}-part2";
              priority = 1;
              size = "100%";
              content = {
                type = "filesystem";
                format = "ext4";
              };
            };
          };
        };
      };
    };
  };
}

I then copied over the files from the (minimal, non-graphical) NixOS live ISO into partition 1, hoping that the instructions on the Arch wiki would generalize to NixOS, but then my live ISO gets stuck with the following error message:

[...]
Timed out waiting for device /dev/root, trying to mount anyway
mounting /dev/root on /iso...
mount: mounting /dev/root on /mnt-root/iso failed: No such file or directory

An error occurred [...]

How can I use my USB flash drive as both a live USB and as a storage device? I found this relevant Discourse link but there was no resolution to the problem there.

I realize this might not be the best place to ask this, but I figured that folks here would have expertise configuring boot partitions correctly.

Couple of questions about NixOS live USBs:

I want to partition my 64 GB USB flash drive into two partitions (FAT32 live USB + ext4 storage), so I used the following disko config:

let
  usb = "/dev/disk/by-id/usb-USB_SanDisk_3.2Gen1_0401a943ae4197a38a6f9070194e9ea2b3fb8dbb7997e05ed1b197c0e28946be4b8f000000000000000000001cf4be6800926418a955810751ab6336-0:0";
in {
  disko.devices = {
    disk = {
      live = {
        type = "disk";
        device = usb;
        content = {
          type = "gpt";
          partitions = {
            ESP = {
              type = "EF00";
              device = "${usb}-part1";
              priority = 0;
              size = "8192M";
              content = {
                type = "filesystem";
                format = "vfat";
              };
            };
            storage = {
              device = "${usb}-part2";
              priority = 1;
              size = "100%";
              content = {
                type = "filesystem";
                format = "ext4";
              };
            };
          };
        };
      };
    };
  };
}

I then copied over the files from the (minimal, non-graphical) NixOS live ISO into partition 1, hoping that the instructions on the Arch wiki would generalize to NixOS, but then my live ISO gets stuck with the following error message:

[...]
Timed out waiting for device /dev/root, trying to mount anyway
mounting /dev/root on /iso...
mount: mounting /dev/root on /mnt-root/iso failed: No such file or directory

An error occurred [...]

How can I use my USB flash drive as both a live USB and as a storage device? I found this relevant Discourse link but there was no resolution to the problem there.

I realize this might not be the best place to ask this, but I figured that folks here would have expertise configuring boot partitions correctly.

For reference, the NixOS manual says I should dd the ISO to the disk directly: sudo dd if=<path-to-image> of=/dev/sdX bs=4M conv=fsync