In reply to @dave:tiredofit.ca
BTRFS Raid 1 will work with Disko May I suggest if it is giving you problems set up your subvolumes on your second disk instead of the first. Otherwise I have a few examples of it here: https://github.com/tiredofit/nixos-config/tree/main/templates/disko

{ lib, ... }:

{
  disko.devices = {
    disk.disk1 = {
      type = "disk";
      device = lib.mkDefault "/dev/sda";
      content = {
        type = "gpt";
        partitions = {
          boot = {
            name = "boot";
            size = "1M";
            type = "EF02";
          };
          esp = {
            name = "ESP";
            size = "500M";
            type = "EF00";
            content = {
              type = "filesystem";
              format = "vfat";
              mountpoint = "/boot";
            };
          };
          zfs = {
            size = "100%";
            content = {
              type = "zfs";
              pool = "zpool";
            };
          };
        };
      };
    };
    zpool = {
      rpool = {
        type = "zpool";
        # mode = "mirror";
        rootFsOptions.compression = "zstd";
        # rootFsOptions."com.sun:auto-snapshot" = "false";

        datasets = {
          "root" = {
            type = "zfs_fs";
            mountpoint = "/";
            options.mountpoint = "legacy";
            postCreateHook = "zfs snapshot rpool/root@blank";
          };
          "local/nix" = {
            type = "zfs_fs";
            mountpoint = "/nix";
            options.mountpoint = "legacy";
          };
          "local/stash" = {
            type = "zfs_fs";
            mountpoint = "/state/stash";
            options.mountpoint = "legacy";
          };

          # safe 
          "safe/home" = {
            type = "zfs_fs";
            mountpoint = "/state/home";
            options.mountpoint = "legacy";
          };
          "safe/persistent" = {
            type = "zfs_fs";
            mountpoint = "/state/root";
            options.mountpoint = "legacy";
          };
        };
      };
    };
  };
}

Anyone that can see the flaw in that config? Error is

+ readarray -t zfs_devices
++ cat /tmp/tmp.gk3UVSF6cj/zfs_rpool
cat: /tmp/tmp.gk3UVSF6cj/zfs_rpool: No such file or directory
+ zpool create -f rpool -R /mnt -O compression=zstd
missing vdev specification
usage:
	create [-fnd] [-o property=value] ...
	    [-O file-system-property=value] ...
	    [-m mountpoint] [-R root] <pool> <vdev> ...
+ rm -rf /tmp/tmp.gk3UVSF6cj

In reply to @lassulus:lassul.us
Pool should be rpool

In reply to @matthewcroughan:defenestrate.it
is there no way to have Nix warn you about that, like "Did you mean rpool?"