diff --git a/include/maxscale/server.h b/include/maxscale/server.h
index 9a71f9209..4820ea9d1 100644
--- a/include/maxscale/server.h
+++ b/include/maxscale/server.h
@@ -60,6 +60,7 @@ typedef struct server_params
 {
     char *name;                 /**< Parameter name */
     char *value;                /**< Parameter value */
+    bool active;                /**< Whether the parameter is valid */
     struct server_params *next; /**< Next Paramter in the linked list */
 } SERVER_PARAM;
 
@@ -254,6 +255,24 @@ SERVER* server_find_destroyed(const char *name, const char *protocol,
  */
 bool server_serialize(const SERVER *server);
 
+/**
+ * @brief Add a server parameter
+ *
+ * @param server Server where the parameter is added
+ * @param name Parameter name
+ * @param value Parameter value
+ */
+void serverAddParameter(SERVER *server, const char *name, const char *value);
+
+/**
+ * @brief Remove a server parameter
+ *
+ * @param server Server to remove the parameter from
+ * @param name The name of the parameter to remove
+ * @return True if a parameter was removed
+ */
+bool serverRemoveParameter(SERVER *server, const char *name);
+
 extern int server_free(SERVER *);
 extern SERVER *server_find_by_unique_name(const char *name);
 extern SERVER *server_find(char *, unsigned short);
@@ -270,7 +289,6 @@ extern void server_set_status_nolock(SERVER *, int);
 extern void server_clear_status_nolock(SERVER *, int);
 extern void server_transfer_status(SERVER *dest_server, SERVER *source_server);
 extern void serverAddMonUser(SERVER *, char *, char *);
-extern void serverAddParameter(SERVER *, char *, char *);
 extern char *serverGetParameter(SERVER *, char *);
 extern void server_update_credentials(SERVER *, char *, char *);
 extern DCB  *server_get_persistent(SERVER *, char *, const char *, int);
diff --git a/server/core/config_runtime.c b/server/core/config_runtime.c
index 17216a3a9..515c349ec 100644
--- a/server/core/config_runtime.c
+++ b/server/core/config_runtime.c
@@ -286,7 +286,20 @@ bool runtime_alter_server(SERVER *server, char *key, char *value)
     }
     else
     {
-        valid = false;
+        if (!serverRemoveParameter(server, key) && !value[0])
+        {
+            valid = false;
+        }
+        else if (value[0])
+        {
+            serverAddParameter(server, key, value);
+
+            /**
+             * It's likely that this parameter is used as a weighting parameter.
+             * We need to update the weights of services that use this.
+             */
+            service_update_weights();
+        }
     }
 
     if (valid)
diff --git a/server/core/maxscale/service.h b/server/core/maxscale/service.h
index 71788c7b1..535efa24f 100644
--- a/server/core/maxscale/service.h
+++ b/server/core/maxscale/service.h
@@ -109,6 +109,9 @@ int      service_isvalid(SERVICE *service);
  */
 bool service_server_in_use(const SERVER *server);
 
+/** Update the server weights used by services */
+void service_update_weights();
+
 /**
  * Alteration of the service configuration
  */
diff --git a/server/core/server.c b/server/core/server.c
index 7565b583f..32e2faf67 100644
--- a/server/core/server.c
+++ b/server/core/server.c
@@ -545,7 +545,11 @@ dprintServer(DCB *dcb, SERVER *server)
         dcb_printf(dcb, "\tServer Parameters:\n");
         while (param)
         {
-            dcb_printf(dcb, "\t                                       %s\t%s\n", param->name, param->value);
+            if (param->active)
+            {
+                dcb_printf(dcb, "\t                                       %s\t%s\n",
+                           param->name, param->value);
+            }
             param = param->next;
         }
     }
@@ -854,26 +858,48 @@ server_update_credentials(SERVER *server, char *user, char *passwd)
  * @param       name    The parameter name
  * @param       value   The parameter value
  */
-void
-serverAddParameter(SERVER *server, char *name, char *value)
+void serverAddParameter(SERVER *server, const char *name, const char *value)
 {
-    name = MXS_STRDUP(name);
-    value = MXS_STRDUP(value);
+    char *my_name = MXS_STRDUP(name);
+    char *my_value = MXS_STRDUP(value);
 
     SERVER_PARAM *param = (SERVER_PARAM *)MXS_MALLOC(sizeof(SERVER_PARAM));
 
-    if (!name || !value || !param)
+    if (!my_name || !my_value || !param)
     {
-        MXS_FREE(name);
-        MXS_FREE(value);
+        MXS_FREE(my_name);
+        MXS_FREE(my_value);
         MXS_FREE(param);
         return;
     }
 
-    param->name = name;
-    param->value = value;
+    param->active = true;
+    param->name = my_name;
+    param->value = my_value;
+
+    spinlock_acquire(&server->lock);
     param->next = server->parameters;
     server->parameters = param;
+    spinlock_release(&server->lock);
+}
+
+bool serverRemoveParameter(SERVER *server, const char *name)
+{
+    bool rval = false;
+    spinlock_acquire(&server->lock);
+
+    for (SERVER_PARAM *p = server->parameters; p; p = p->next)
+    {
+        if (strcmp(p->name, name) == 0 && p->active)
+        {
+            p->active = false;
+            rval = true;
+            break;
+        }
+    }
+
+    spinlock_release(&server->lock);
+    return rval;
 }
 
 /**
@@ -908,7 +934,7 @@ serverGetParameter(SERVER *server, char *name)
 
     while (param)
     {
-        if (strcmp(param->name, name) == 0)
+        if (strcmp(param->name, name) == 0 && param->active)
         {
             return param->value;
         }
@@ -1142,6 +1168,14 @@ static bool create_server_config(const SERVER *server, const char *filename)
         dprintf(file, "persistmaxtime=%ld\n", server->persistmaxtime);
     }
 
+    for (SERVER_PARAM *p = server->parameters; p; p = p->next)
+    {
+        if (p->active)
+        {
+            dprintf(file, "%s=%s\n", p->name, p->value);
+        }
+    }
+
     if (server->server_ssl)
     {
         dprintf(file, "ssl=required\n");
diff --git a/server/core/service.c b/server/core/service.c
index 9ad99e101..4dafcb6f1 100644
--- a/server/core/service.c
+++ b/server/core/service.c
@@ -2271,7 +2271,7 @@ static void service_calculate_weights(SERVICE *service)
 
                     if (perc == 0)
                     {
-                        MXS_ERROR("Weighting parameter '%s' with a value of %d for"
+                        MXS_WARNING("Weighting parameter '%s' with a value of %d for"
                                   " server '%s' rounds down to zero with total weight"
                                   " of %d for service '%s'. No queries will be "
                                   "routed to this server as long as a server with"
@@ -2300,6 +2300,18 @@ static void service_calculate_weights(SERVICE *service)
     }
 }
 
+void service_update_weights()
+{
+    spinlock_acquire(&service_spin);
+
+    for (SERVICE *service = allServices; service; service = service->next)
+    {
+        service_calculate_weights(service);
+    }
+
+    spinlock_release(&service_spin);
+}
+
 bool service_server_in_use(const SERVER *server)
 {
     bool rval = false;