Assuming you got your rrd4j persistence working in the end? I’m still struggling…
2017-03-18 00:00:31.435 [INFO ] [el.core.internal.ModelRepositoryImpl] - Refreshing model 'rrd4j.persist'
2017-03-18 00:00:31.457 [ERROR] [.core.internal.folder.FolderObserver] - Error handling update of file '/etc/openhab2/persistence/rrd4j.persist': null.
java.lang.NullPointerException
at org.eclipse.smarthome.core.scheduler.ExpressionThreadPoolManager$ExpressionThreadPoolExecutor.removeFutures(ExpressionThreadPoolManager.java:321)[98:org.eclipse.smarthome.core:0.9.0.b4]
at org.eclipse.smarthome.core.scheduler.ExpressionThreadPoolManager$ExpressionThreadPoolExecutor.remove(ExpressionThreadPoolManager.java:291)[98:org.eclipse.smarthome.core:0.9.0.b4]
at org.eclipse.smarthome.core.scheduler.ExpressionThreadPoolManager$ExpressionThreadPoolExecutor.remove(ExpressionThreadPoolManager.java:308)[98:org.eclipse.smarthome.core:0.9.0.b4]
at org.eclipse.smarthome.core.persistence.internal.PersistenceManagerImpl.removeTimers(PersistenceManagerImpl.java:321)[103:org.eclipse.smarthome.core.persistence:0.9.0.b4]
at org.eclipse.smarthome.core.persistence.internal.PersistenceManagerImpl.stopEventHandling(PersistenceManagerImpl.java:377)[103:org.eclipse.smarthome.core.persistence:0.9.0.b4]
at org.eclipse.smarthome.core.persistence.internal.PersistenceManagerImpl.removeConfig(PersistenceManagerImpl.java:348)[103:org.eclipse.smarthome.core.persistence:0.9.0.b4]
at org.eclipse.smarthome.model.persistence.internal.PersistenceModelManager.modelChanged(PersistenceModelManager.java:85)[125:org.eclipse.smarthome.model.persistence:0.9.0.b4]
at org.eclipse.smarthome.model.core.internal.ModelRepositoryImpl.notifyListeners(ModelRepositoryImpl.java:207)[122:org.eclipse.smarthome.model.core:0.9.0.b4]
at org.eclipse.smarthome.model.core.internal.ModelRepositoryImpl.addOrRefreshModel(ModelRepositoryImpl.java:120)[122:org.eclipse.smarthome.model.core:0.9.0.b4]
at org.eclipse.smarthome.model.core.internal.folder.FolderObserver.checkFile(FolderObserver.java:272)[122:org.eclipse.smarthome.model.core:0.9.0.b4]
at org.eclipse.smarthome.model.core.internal.folder.FolderObserver.access$1(FolderObserver.java:265)[122:org.eclipse.smarthome.model.core:0.9.0.b4]
at org.eclipse.smarthome.model.core.internal.folder.FolderObserver$WatchQueueReader.processWatchEvent(FolderObserver.java:146)[122:org.eclipse.smarthome.model.core:0.9.0.b4]
at org.eclipse.smarthome.core.service.AbstractWatchQueueReader.run(AbstractWatchQueueReader.java:122)[98:org.eclipse.smarthome.core:0.9.0.b4]
at java.lang.Thread.run(Thread.java:745)[:1.8.0_112]