Hi,
Not sure if this is a bug, or a cannot fix, but;
If rrdcached is running and "$config['rrdcached'] = "unix:/var/run/rrdcached.sock" is configured in config.php, the graphs for the Unix Agent do not work.
I can understand why Smokeping does not work if it does not know how to read and write from the unix socket (so we created a link to SmokePing in the Globe menu). But I cannot think why the Observium UNIX Agent does not work, as that is a part of Observium, and the rest of observium works with rrdcached.
I can only guess that the UNIX Agent poller is not writing to the UNIX socket and is still trying to write to /opt/observium/rrd/, however when I disable RRDCache and remove the rrdcached line from config.php, all the old data appears. This makes me think that the UNIX Agent poller is writting to the socket correctly, and it is just Observium itself that is failing to revert to reading from the UNIX socket for Applications etc.
Cheers, Andy.