If the poller master doesn't complete in time and ends up with overlapping jobs, neither job will ever complete because both running jobs will think they are the master and wait for the remaining node to exit.
When using rrdcached [rrdtool.inc.php](includes/rrdtool.inc.php#L163) already adds the necessary options. Collectd.inc.php adds them again which breaks drawing the graphs.
Currently users cannot use the check_mk apache plugin to monitor the apache instance that is running librenms. Excluding server-status from the rewrite rules allows users to use mod_status.