diff --git a/src/api2/node/disks/directory.rs b/src/api2/node/disks/directory.rs
index 57add02b..62f46343 100644
--- a/src/api2/node/disks/directory.rs
+++ b/src/api2/node/disks/directory.rs
@@ -204,6 +204,11 @@ pub fn create_datastore_disk(
         }
     }
 
+    let (mount_unit_path, _) = datastore_mount_unit_path_info(&mount_point);
+    if std::path::PathBuf::from(&mount_unit_path).exists() {
+        bail!("systemd mount unit '{mount_unit_path}' already exists");
+    }
+
     let upid_str = WorkerTask::new_thread(
         "dircreate",
         Some(name.clone()),