Collectd stats collection issue..

FlightAware ADS-B Flight Tracking
1

This started this week. At times collectd seems to stop collecting stats for certain parameters. In the last two times it stopped the signal level and the noise level seems to be missing while other stats like the range data is fine. Here’s two graphs from the same time period this evening. Would anyone have a place for me to start and try to figure this out?

http://tjowen.ddns.net/collectd/graph-images/dump1090-rpi-signal-6h.png
http://tjowen.ddns.net/collectd/graph-images/dump1090-rpi-range-6h.png

2

Are you seeing any errors in the log from collectd? If it’s having problems writing to the rrd files for some reason, it usually has some kind of output there.

3

Would you know where the collectd.log is located? I cannot find it.

It seems to stop writing to 4 files in particular, dbfs-noise, dbfs-peak_signal, dbfs-signal & strong-signal.

-rw-r–r-- 1 root root 307516 Feb 19 22:59 dump1090_aircraft-recent.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_cpu-background.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_cpu-demod.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_cpu-reader.rrd
-rw-r–r-- 1 root root 154692 Feb 19 19:52 dump1090_dbfs-noise.rrd
-rw-r–r-- 1 root root 154692 Feb 19 19:52 dump1090_dbfs-peak_signal.rrd
-rw-r–r-- 1 root root 154692 Feb 19 19:52 dump1090_dbfs-signal.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_messages-local_accepted_0.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_messages-local_accepted_1.rrd
-rw-r–r-- 1 root root 154692 Jul 13 2015 dump1090_messages-local_accepted_2.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_messages-local_accepted.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_messages-positions.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_messages-remote_accepted_0.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_messages-remote_accepted_1.rrd
-rw-r–r-- 1 root root 154692 Jul 13 2015 dump1090_messages-remote_accepted_2.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_messages-remote_accepted.rrd
-rw-r–r-- 1 root root 154692 Feb 19 19:52 dump1090_messages-strong_signals.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_mlat-recent.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_range-max_range.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_tracks-all.rrd
-rw-r–r-- 1 root root 154692 Feb 19 22:59 dump1090_tracks-single_message.rrd

4

I get the same thing when I enable
–modeac
in /etc/default/dump1090-mutability
remove it and the stats return.

5

I’m not using the --modeac option.
thanks, Tom

6

OK, I’ve edited the collectd.conf file to now create and log to the /var/log/collectd.log file. I will keep an eye on it and see what gets logged.
…Tom

7

Here’s two log entries from my new log file following a restart.

[2016-02-19 23:58:04] uc_update: Value too old: name = localhost/dump1090-rpi/dump1090_messages-strong_signals; value time = 1455940682.600; last cache update = 1455940682.600;

[2016-02-19 23:58:04] Filter subsystem: Built-in target `write’: Dispatching value to all write plugins failed with status -1.

8

Can anyone shed some light on the error message above?

9

It’s a quirk of collectd, it doesn’t like being given the same timestamp twice.
But dump1090 reports the timestamp from the json files (which is the right thing to do)
So if the json file timestamp doesn’t increase between two collectd polls. you get that error.

It’s generally harmless if the json file really is being updated.

10

Any thoughts on why collectd would stop processing only 4 of the .rrd files with only a log entry similar to the above in common? This issue started this week and has occured twice a couple days apart. All I did to resolve was to reboot.

…Tom