Hey, I'm experiencing an issue with postMountHook. I have a zfs pool that looks roughly like this:

{
  type = "zpool";

  options = {
    ashift = "12";
  };

  rootFsOptions = {
    acltype = "posix";
    compression = "on";
    mountpoint = "none";
    overlay = "off";
    xattr = "sa";
  };

  datasets =
    let
      mkDataset = lib.attrsets.recursiveUpdate {
        type = "zfs_fs";
      };
    in
    {
      "rootfs" = mkDataset {
        mountpoint = "/";
      };

      "home" = mkDataset {
        mountpoint = "/home";
      };

      "home/user" = mkDataset {
        name = "home/${config.custom.username}";
        mountpoint = "/home/${config.custom.username}";

        options = {
          mountpoint = "/home/${config.custom.username}";
          encryption = "on";
          keyformat = "passphrase";
          keylocation = "prompt";
          "com.sun:auto-snapshot" = "true";
        };

        postMountHook = ''
          # ...
        '';
      };
    };
}

(other datasets omitted for the sake of brevity)

Initially I did not specify options.mountpoint, and ran into the problem that my dataset was not mounted by the time postMountHook got executed. I saw the zfs example in the disko repo using both mountpoint and options.mountpoint, so I figured I'd give it a shot. Now the problem is that it remains mounted when the main disko script tries to mount the rest, which then fails because /mnt is not empty... The error message:

+ findmnt nixos/rootfs /mnt/
+ mount nixos/rootfs /mnt/ -o X-mount.mkdir -o defaults -o zfsutil -t zfs
zfs_mount_at() failed: directory is not empty+ rm -rf /tmp/tmp.aSJMo4rNbE

I don't know if I'm doing something wrong or if the script generation is just broken?

Hey, I'm experiencing an issue with postMountHook. I have a zfs pool that looks roughly like this:

{
  type = "zpool";

  options = {
    ashift = "12";
  };

  rootFsOptions = {
    acltype = "posix";
    compression = "on";
    mountpoint = "none";
    overlay = "off";
    xattr = "sa";
  };

  datasets =
    let
      mkDataset = lib.attrsets.recursiveUpdate {
        type = "zfs_fs";
      };
    in
    {
      "rootfs" = mkDataset {
        mountpoint = "/";
      };

      "home" = mkDataset {
        mountpoint = "/home";
      };

      "home/${config.custom.username}" = mkDataset {
        mountpoint = "/home/${config.custom.username}";

        options = {
          mountpoint = "/home/${config.custom.username}";
          encryption = "on";
          keyformat = "passphrase";
          keylocation = "prompt";
          "com.sun:auto-snapshot" = "true";
        };

        postMountHook = ''
          # ...
        '';
      };
    };
}

(other datasets omitted for the sake of brevity)

Initially I did not specify options.mountpoint, and ran into the problem that my dataset was not mounted by the time postMountHook got executed. I saw the zfs example in the disko repo using both mountpoint and options.mountpoint, so I figured I'd give it a shot. Now the problem is that it remains mounted when the main disko script tries to mount the rest, which then fails because /mnt is not empty... The error message:

+ findmnt nixos/rootfs /mnt/
+ mount nixos/rootfs /mnt/ -o X-mount.mkdir -o defaults -o zfsutil -t zfs
zfs_mount_at() failed: directory is not empty+ rm -rf /tmp/tmp.aSJMo4rNbE

I don't know if I'm doing something wrong or if the script generation is just broken?

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.