diff --git a/scripts/ha/resize-data-disk.sh b/scripts/ha/resize-data-disk.sh
index 4379cd9..13e6dc1 100755
--- a/scripts/ha/resize-data-disk.sh
+++ b/scripts/ha/resize-data-disk.sh
@@ -204,17 +204,13 @@ rescan_node() {
   local node_name=$1 run_fn=$2
 
   # Resolve block device name from the stable by-id symlink on the guest.
+  # Read-only lookup — safe to run even in dry-run so we show the real device.
   local blk_dev=""
-  if ! $DRY_RUN; then
-    blk_dev=$($run_fn "bash -c 'basename \$(readlink -f /dev/disk/by-id/${DATA_DISK_BYID})'" 2>/dev/null || true)
-  fi
+  blk_dev=$($run_fn "bash -c 'basename \$(readlink -f /dev/disk/by-id/${DATA_DISK_BYID})'" 2>/dev/null || true)
   if [[ -z "$blk_dev" ]]; then
-    # Fall back: scsi1 → index 1 → sdb, scsi2 → sdc, etc.
-    local slot_idx
-    slot_idx=$(echo "$DATA_DISK_SLOT" | grep -oE '[0-9]+$' || echo "1")
-    blk_dev=$(printf "sd%s" "$(echo "abcdefghij" | cut -c$((slot_idx + 1)))")
-    echo "  WARNING: could not resolve /dev/disk/by-id/${DATA_DISK_BYID} on $node_name;" \
-         "falling back to /dev/${blk_dev}" >&2
+    echo "  ERROR: /dev/disk/by-id/${DATA_DISK_BYID} not found on $node_name" >&2
+    echo "         Check DATA_DISK_BYID or DATA_DISK_SLOT configuration." >&2
+    exit 1
   fi
 
   echo "  ${DRY_PREFIX}Rescanning /dev/${blk_dev} on ${node_name}..."