diff --git a/include/Cluster.h b/include/Cluster.h
index 2aa93e5e8d..274720ff3f 100644
--- a/include/Cluster.h
+++ b/include/Cluster.h
@@ -32,20 +32,13 @@ class Cluster : public PoolObjectSQL
 public:
 
     /**
-     * Returns the SYSTEM_DS attribute, or the system DS id if it is not defined
+     * Returns the SYSTEM_DS attribute
      *
-     * @return the SYSTEM_DS attribute, or the system DS id if it is not defined
+     * @return the SYSTEM_DS attribute
      */
     int get_ds_id()
     {
-        int ds_id;
-
-        if ( obj_template->get("SYSTEM_DS", ds_id) == false )
-        {
-            ds_id = DatastorePool::SYSTEM_DS_ID;
-        }
-
-        return ds_id;
+        return system_ds;
     }
 
     /**
@@ -103,29 +96,7 @@ public:
      *    @param error_msg Error message, if any
      *    @return 0 on success
      */
-    int add_datastore(int id, string& error_msg)
-    {
-        // TODO: should fail for any system DS?
-        if ( id == DatastorePool::SYSTEM_DS_ID )
-        {
-            ostringstream oss;
-            oss << "Datastore '"<< DatastorePool::SYSTEM_DS_NAME
-                << "' cannot be added to any cluster.";
-
-            error_msg = oss.str();
-
-            return -1;
-        }
-
-        int rc = datastores.add_collection_id(id);
-
-        if ( rc < 0 )
-        {
-            error_msg = "Datastore ID is already in the cluster set.";
-        }
-
-        return rc;
-    }
+    int add_datastore(int id, string& error_msg);
 
     /**
      *  Deletes this datastore ID from the set.
@@ -133,17 +104,7 @@ public:
      *    @param error_msg Error message, if any
      *    @return 0 on success
      */
-    int del_datastore(int id, string& error_msg)
-    {
-        int rc = datastores.del_collection_id(id);
-
-        if ( rc < 0 )
-        {
-            error_msg = "Datastore ID is not part of the cluster set.";
-        }
-
-        return rc;
-    }
+    int del_datastore(int id, string& error_msg);
 
     /**
      *  Adds this vnet ID to the set.
@@ -219,13 +180,18 @@ private:
     virtual ~Cluster(){};
 
     // *************************************************************************
-    // Object Collections (Private)
+    // Attributes (Private)
     // *************************************************************************
 
     ObjectCollection hosts;
     ObjectCollection datastores;
     ObjectCollection vnets;
 
+    /**
+     * System datastore id
+     */
+    int system_ds;
+
     // *************************************************************************
     // DataBase implementation (Private)
     // *************************************************************************
diff --git a/src/cluster/Cluster.cc b/src/cluster/Cluster.cc
index 8c25673843..cc220f55e3 100644
--- a/src/cluster/Cluster.cc
+++ b/src/cluster/Cluster.cc
@@ -45,7 +45,8 @@ Cluster::Cluster(
             PoolObjectSQL(id,CLUSTER,name,-1,-1,"","",table),
             hosts("HOSTS"),
             datastores("DATASTORES"),
-            vnets("VNETS")
+            vnets("VNETS"),
+            system_ds(DatastorePool::SYSTEM_DS_ID)
 {
     if (cl_template != 0)
     {
@@ -113,6 +114,82 @@ string& Cluster::get_ds_location(string &ds_location)
     return ds_location;
 }
 
+/* ------------------------------------------------------------------------ */
+/* ------------------------------------------------------------------------ */
+
+int Cluster::add_datastore(int id, string& error_msg)
+{
+    if ( id == DatastorePool::SYSTEM_DS_ID )
+    {
+        ostringstream oss;
+        oss << "Datastore '"<< DatastorePool::SYSTEM_DS_NAME
+            << "' cannot be added to any cluster.";
+
+        error_msg = oss.str();
+
+        return -1;
+    }
+
+    // TODO: Do not lock DS here, take ds_type as an argument
+
+    Datastore *ds = Nebula::instance().get_dspool()->get(id, true);
+
+    if ( ds == 0 )
+    {
+        return -1;
+    }
+
+    Datastore::DatastoreType ds_type = ds->get_type();
+
+    ds->unlock();
+
+    if ( ds_type == Datastore::SYSTEM_DS )
+    {
+        if ( system_ds != DatastorePool::SYSTEM_DS_ID )
+        {
+            ostringstream oss;
+            oss << "Cluster " << oid << " already contains the System Datastore "
+                << system_ds << ".";
+
+            error_msg = oss.str();
+
+            return -1;
+        }
+    }
+
+    int rc = datastores.add_collection_id(id);
+
+    if ( rc < 0 )
+    {
+        error_msg = "Datastore ID is already in the cluster set.";
+    }
+    else if ( ds_type == Datastore::SYSTEM_DS )
+    {
+        system_ds = id;
+    }
+
+    return rc;
+}
+
+/* ------------------------------------------------------------------------ */
+/* ------------------------------------------------------------------------ */
+
+int Cluster::del_datastore(int id, string& error_msg)
+{
+    int rc = datastores.del_collection_id(id);
+
+    if ( rc < 0 )
+    {
+        error_msg = "Datastore ID is not part of the cluster set.";
+    }
+    else if ( system_ds == id )
+    {
+        system_ds = DatastorePool::SYSTEM_DS_ID;
+    }
+
+    return rc;
+}
+
 /* ************************************************************************ */
 /* Cluster :: Database Access Functions                                     */
 /* ************************************************************************ */
@@ -215,8 +292,9 @@ string& Cluster::to_xml(string& xml) const
 
     oss <<
     "<CLUSTER>"  <<
-        "<ID>"   << oid  << "</ID>"   <<
-        "<NAME>" << name << "</NAME>" <<
+        "<ID>"          << oid          << "</ID>"          <<
+        "<NAME>"        << name         << "</NAME>"        <<
+        "<SYSTEM_DS>"   << system_ds    << "</SYSTEM_DS>"   <<
 
         hosts.to_xml(host_collection_xml)    <<
         datastores.to_xml(ds_collection_xml) <<
@@ -241,8 +319,9 @@ int Cluster::from_xml(const string& xml)
     update_from_str(xml);
 
     // Get class base attributes
-    rc += xpath(oid, "/CLUSTER/ID",   -1);
-    rc += xpath(name,"/CLUSTER/NAME", "not_found");
+    rc += xpath(oid,        "/CLUSTER/ID",          -1);
+    rc += xpath(name,       "/CLUSTER/NAME",        "not_found");
+    rc += xpath(system_ds,  "/CLUSTER/SYSTEM_DS",   -1);
 
     // Set oneadmin as the owner
     set_user(0,"");