diff --git a/example/complex.nix b/example/complex.nix
index 58e215b..501de2a 100644
--- a/example/complex.nix
+++ b/example/complex.nix
@@ -163,21 +163,21 @@
 
         datasets = {
           zfs_fs = {
-            zfs_type = "filesystem";
+            type = "zfs_fs";
             mountpoint = "/zfs_fs";
             options."com.sun:auto-snapshot" = "true";
           };
           zfs_unmounted_fs = {
-            zfs_type = "filesystem";
+            type = "zfs_fs";
             options.mountpoint = "none";
           };
           zfs_legacy_fs = {
-            zfs_type = "filesystem";
+            type = "zfs_fs";
             options.mountpoint = "legacy";
             mountpoint = "/zfs_legacy_fs";
           };
           zfs_testvolume = {
-            zfs_type = "volume";
+            type = "zfs_volume";
             size = "10M";
             content = {
               type = "filesystem";
diff --git a/example/zfs-over-legacy.nix b/example/zfs-over-legacy.nix
index 25d0f02..2a5a2c6 100644
--- a/example/zfs-over-legacy.nix
+++ b/example/zfs-over-legacy.nix
@@ -50,11 +50,11 @@
         type = "zpool";
         datasets = {
           "root" = {
-            zfs_type = "filesystem";
+            type = "zfs_fs";
             options.mountpoint = "none";
           };
           "root/zfs_fs" = {
-            zfs_type = "filesystem";
+            type = "zfs_fs";
             mountpoint = "/zfs_fs";
             options."com.sun:auto-snapshot" = "true";
           };
diff --git a/example/zfs.nix b/example/zfs.nix
index 3700018..4fd2bd9 100644
--- a/example/zfs.nix
+++ b/example/zfs.nix
@@ -64,21 +64,21 @@
 
         datasets = {
           zfs_fs = {
-            zfs_type = "filesystem";
+            type = "zfs_fs";
             mountpoint = "/zfs_fs";
             options."com.sun:auto-snapshot" = "true";
           };
           zfs_unmounted_fs = {
-            zfs_type = "filesystem";
+            type = "zfs_fs";
             options.mountpoint = "none";
           };
           zfs_legacy_fs = {
-            zfs_type = "filesystem";
+            type = "zfs_fs";
             options.mountpoint = "legacy";
             mountpoint = "/zfs_legacy_fs";
           };
           zfs_testvolume = {
-            zfs_type = "volume";
+            type = "zfs_volume";
             size = "10M";
             content = {
               type = "filesystem";
@@ -87,8 +87,7 @@
             };
           };
           encrypted = {
-            zfs_type = "filesystem";
-            size = "20M";
+            type = "zfs_fs";
             options = {
               mountpoint = "none";
               encryption = "aes-256-gcm";
@@ -97,8 +96,7 @@
             };
           };
           "encrypted/test" = {
-            zfs_type = "filesystem";
-            size = "2M";
+            type = "zfs_fs";
             mountpoint = "/zfs_crypted";
           };
         };
diff --git a/types/default.nix b/types/default.nix
index 5f5eeec..ec2f4f5 100644
--- a/types/default.nix
+++ b/types/default.nix
@@ -133,7 +133,7 @@ rec {
           || lib.hasSuffix "Hook" n
           || isAttrsOfSubmodule o
           # TODO don't hardcode diskoLib.subType options.
-          || n == "content" || n == "partitions"
+          || n == "content" || n == "partitions" || n == "datasets"
         );
       in
       lib.toShellVars
@@ -348,6 +348,8 @@ rec {
     zfs = ./zfs.nix;
     zpool = ./zpool.nix;
     zfs_dataset = ./zfs_dataset.nix;
+    zfs_fs = ./zfs_fs.nix;
+    zfs_volume = ./zfs_volume.nix;
     mdadm = ./mdadm.nix;
     mdraid = ./mdraid.nix;
     luks = ./luks.nix;
diff --git a/types/zfs_dataset.nix b/types/zfs_fs.nix
similarity index 60%
rename from types/zfs_dataset.nix
rename to types/zfs_fs.nix
index c3eadbc..a9ad950 100644
--- a/types/zfs_dataset.nix
+++ b/types/zfs_fs.nix
@@ -7,15 +7,11 @@
       description = "Name of the dataset";
     };
     type = lib.mkOption {
-      type = lib.types.enum [ "zfs_dataset" ];
-      default = "zfs_dataset";
+      type = lib.types.enum [ "zfs_fs" ];
+      default = "zfs_fs";
       internal = true;
       description = "Type";
     };
-    zfs_type = lib.mkOption {
-      type = lib.types.enum [ "filesystem" "volume" ];
-      description = "The type of the dataset";
-    };
     options = lib.mkOption {
       type = lib.types.attrsOf lib.types.str;
       default = { };
@@ -27,46 +23,30 @@
       description = "Mount options";
     };
 
-    # filesystem options
     mountpoint = lib.mkOption {
       type = lib.types.nullOr optionTypes.absolute-pathname;
       default = null;
       description = "Path to mount the dataset to";
     };
 
-    # volume options
-    size = lib.mkOption {
-      type = lib.types.nullOr lib.types.str; # TODO size
-      default = null;
-      description = "Size of the dataset";
-    };
-
-    content = diskoLib.partitionType;
     _meta = lib.mkOption {
       internal = true;
       readOnly = true;
       type = lib.types.functionTo diskoLib.jsonType;
-      default = dev:
-        lib.optionalAttrs (config.content != null) (config.content._meta dev);
+      default = dev: {};
       description = "Metadata";
     };
     _create = diskoLib.mkCreateOption {
       inherit config options;
       default = { zpool }: ''
         zfs create ${zpool}/${config.name} \
-          ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-o ${n}=${v}") config.options)} \
-          ${lib.optionalString (config.zfs_type == "volume") "-V ${config.size}"}
-        ${lib.optionalString (config.zfs_type == "volume") ''
-          udevadm trigger --subsystem-match=block; udevadm settle
-          ${lib.optionalString (config.content != null) (config.content._create {dev = "/dev/zvol/${zpool}/${config.name}";})}
-        ''}
+          ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-o ${n}=${v}") config.options)}
       '';
     };
     _mount = diskoLib.mkMountOption {
       inherit config options;
       default = { zpool }:
-        lib.optionalAttrs (config.zfs_type == "volume" && config.content != null) (config.content._mount { dev = "/dev/zvol/${zpool}/${config.name}"; }) //
-        lib.optionalAttrs (config.zfs_type == "filesystem" && config.options.mountpoint or "" != "none") {
+        lib.optionalAttrs (config.options.mountpoint or "" != "none") {
           fs.${config.mountpoint} = ''
             if ! findmnt ${zpool}/${config.name} "${rootMountPoint}${config.mountpoint}" > /dev/null 2>&1; then
               mount ${zpool}/${config.name} "${rootMountPoint}${config.mountpoint}" \
@@ -82,22 +62,22 @@
       internal = true;
       readOnly = true;
       default = zpool:
-        (lib.optional (config.zfs_type == "volume" && config.content != null) (config.content._config "/dev/zvol/${zpool}/${config.name}")) ++
-        (lib.optional (config.zfs_type == "filesystem" && config.options.mountpoint or "" != "none") {
+        lib.optional (config.options.mountpoint or "" != "none") {
           fileSystems.${config.mountpoint} = {
             device = "${zpool}/${config.name}";
             fsType = "zfs";
             options = config.mountOptions ++ lib.optional ((config.options.mountpoint or "") != "legacy") "zfsutil";
           };
-        });
+        };
       description = "NixOS configuration";
     };
     _pkgs = lib.mkOption {
       internal = true;
       readOnly = true;
       type = lib.types.functionTo (lib.types.listOf lib.types.package);
-      default = pkgs: [ pkgs.util-linux ] ++ lib.optionals (config.content != null) (config.content._pkgs pkgs);
+      default = pkgs: [ pkgs.util-linux ];
       description = "Packages";
     };
   };
 }
+
diff --git a/types/zfs_volume.nix b/types/zfs_volume.nix
new file mode 100644
index 0000000..2609ed6
--- /dev/null
+++ b/types/zfs_volume.nix
@@ -0,0 +1,73 @@
+{ config, options, lib, diskoLib, optionTypes, rootMountPoint, ... }:
+{
+  options = {
+    name = lib.mkOption {
+      type = lib.types.str;
+      default = config._module.args.name;
+      description = "Name of the dataset";
+    };
+    type = lib.mkOption {
+      type = lib.types.enum [ "zfs_volume" ];
+      default = "zfs_volume";
+      internal = true;
+      description = "Type";
+    };
+    options = lib.mkOption {
+      type = lib.types.attrsOf lib.types.str;
+      default = { };
+      description = "Options to set for the dataset";
+    };
+    mountOptions = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [ "defaults" ];
+      description = "Mount options";
+    };
+
+    # volume options
+    size = lib.mkOption {
+      type = lib.types.nullOr lib.types.str; # TODO size
+      default = null;
+      description = "Size of the dataset";
+    };
+
+    content = diskoLib.partitionType;
+
+    _meta = lib.mkOption {
+      internal = true;
+      readOnly = true;
+      type = lib.types.functionTo diskoLib.jsonType;
+      default = dev:
+        lib.optionalAttrs (config.content != null) (config.content._meta dev);
+      description = "Metadata";
+    };
+    _create = diskoLib.mkCreateOption {
+      inherit config options;
+      default = { zpool }: ''
+        zfs create ${zpool}/${config.name} \
+          ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-o ${n}=${v}") config.options)} -V ${config.size}
+        udevadm trigger --subsystem-match=block; udevadm settle
+        ${lib.optionalString (config.content != null) (config.content._create {dev = "/dev/zvol/${zpool}/${config.name}";})}
+      '';
+    };
+    _mount = diskoLib.mkMountOption {
+      inherit config options;
+      default = { zpool }:
+        lib.optionalAttrs (config.content != null) (config.content._mount { dev = "/dev/zvol/${zpool}/${config.name}"; });
+    };
+    _config = lib.mkOption {
+      internal = true;
+      readOnly = true;
+      default = zpool:
+        lib.optional (config.content != null) (config.content._config "/dev/zvol/${zpool}/${config.name}");
+      description = "NixOS configuration";
+    };
+    _pkgs = lib.mkOption {
+      internal = true;
+      readOnly = true;
+      type = lib.types.functionTo (lib.types.listOf lib.types.package);
+      default = pkgs: [ pkgs.util-linux ] ++ lib.optionals (config.content != null) (config.content._pkgs pkgs);
+      description = "Packages";
+    };
+  };
+}
+
diff --git a/types/zpool.nix b/types/zpool.nix
index 0a7e66a..4c70bd6 100644
--- a/types/zpool.nix
+++ b/types/zpool.nix
@@ -38,7 +38,8 @@
       description = "Options to pass to mount";
     };
     datasets = lib.mkOption {
-      type = lib.types.attrsOf subTypes.zfs_dataset;
+      type = lib.types.attrsOf (diskoLib.subType { inherit (subTypes) zfs_fs zfs_volume; });
+      # type = lib.types.attrsOf subTypes.zfs_fs;
       description = "List of datasets to define";
     };
     _meta = lib.mkOption {
@@ -72,7 +73,7 @@
             zpool list '${config.name}' >/dev/null 2>/dev/null || zpool import '${config.name}'
             ${lib.concatMapStrings (x: x.dev or "") (lib.attrValues datasetMounts)}
           '';
-          fs = datasetMounts.fs // lib.optionalAttrs (config.mountpoint != null) {
+          fs = (datasetMounts.fs or {}) // lib.optionalAttrs (config.mountpoint != null) {
             ${config.mountpoint} = ''
               if ! findmnt ${config.name} "${rootMountPoint}${config.mountpoint}" > /dev/null 2>&1; then
                 mount ${config.name} "${rootMountPoint}${config.mountpoint}" \