* - loadMonitor : Name of a class used to fetch server lag and load.
* - readOnlyReason : Reason the master DB is read-only if so [optional]
* - waitTimeout : Maximum time to wait for replicas for consistency [optional]
+ * - maxLag: Avoid replica DB servers with more lag than this [optional]
* - srvCache : BagOStuff object for server cache [optional]
* - wanCache : WANObjectCache object [optional]
* - chronologyProtector: ChronologyProtector object [optional]