rrdtool plugin errors and missing interfaces graph

Morning -

After doing some testing in a VM the last week I have decided to put OMV on physical hardware for more in depth testing. Things are going well but I have run into an issue where rrdtool plugin complains in syslog about updates to graphs failing. Oddly, all graphs display fine except the interfaces graph. When selected, I see nothing; no refresh button, no graph, just white space. This all seemed to happen a couple reboots ago and after installing OMV-Plugins.org repo. I did not experience this issue with the VM. Clearly time between updates is out of sync.

I've attached a screencap of the errors I'm getting. Any help is appreciated.

Well, fixed the errors by removing all .rrd files from /var/lib/collectd/localhost/(df)(cpuX)(interfaces)(memory) directories and letting them be recreated but still am not seeing anything on the interfaces tab.

I did. I couldn't get a nic to come up otherwise after a reboot and saw nothing in /etc/network/interfaces about the device so added it manually. Link worked after that but I guess that was when the graphs stopped working. I've since reset the nic via OVM and am now seeing data in the interfaces report. Thanks.

Doesn't seem to be much difference between what I had in there minus allow-hotplug and dns-servers entries. Why would changing interfaces manually break that?