diff --git a/jupiter/configuration.nix b/jupiter/configuration.nix
index 09ea8b7..60bd4c4 100644
--- a/jupiter/configuration.nix
+++ b/jupiter/configuration.nix
@@ -14,11 +14,15 @@
   boot.loader.systemd-boot.enable = true;
   boot.loader.efi.canTouchEfiVariables = true;
 
-  # ---- NAS data disk ----
-  # Existing data filesystem — mounted, NOT formatted (kept out of disko).
-  # Set the id from `ls -l /dev/disk/by-id` (or by-uuid). Adjust fsType.
-  # fileSystems."/mnt/data" = {
-  #   device = "/dev/disk/by-id/CHANGE-ME-data-disk";
-  #   fsType = "ext4";
-  # };
+  # ---- NAS data array ----
+  # Existing ext4 on the mdadm RAID0 over sda+sdb (md0, 29.1T).
+  # Mounted, NOT formatted; kept out of disko so it is never wiped.
+  # ⚠️ RAID0 = no redundancy: either 16TB disk failing loses ALL data.
+  boot.swraid.enable = true;  # assemble the mdadm array at boot
+  fileSystems."/mnt/data" = {
+    # fs UUID (stable) — the array may enumerate as /dev/md127, so avoid /dev/md0.
+    device = "/dev/disk/by-uuid/dadbff6f-652e-49b2-bfed-eb1308ab8b78";
+    fsType = "ext4";
+    options = [ "nofail" ];  # don't block boot if the array is degraded/absent
+  };
 }
diff --git a/jupiter/disk-config.nix b/jupiter/disk-config.nix
index efc2833..e0bde3b 100644
--- a/jupiter/disk-config.nix
+++ b/jupiter/disk-config.nix
@@ -14,7 +14,8 @@
 {
   disko.devices.disk.os = {
     type = "disk";
-    device = "/dev/disk/by-id/CHANGE-ME-os-disk";
+    # ZimaBlade internal eMMC (29.1G). NOT the data RAID (sda/sdb/md0).
+    device = "/dev/disk/by-id/mmc-C9A551_0xaa057ad0";
     content = {
       type = "gpt";
       partitions = {