Conflict between rrd4j and my.openhab persistence?

Add-ons Persistence Services
1

I had a good working rrd4j persistence with working graphs but after enabling the persistence for my.openhab I no longer see the graphs.
Also min and max values are not calculated correctly anymore.

my rrd4j contents:
// persistence strategies have a name and a definition and are referred to in the “Items” section
Strategies {
everyMinute : “0 * * * * ?”
everyHour : “0 0 * * * ?”
everyDay : “0 0 0 * * ?”
default = everyChange
}

Items {
// DemoSwitch,NoOfLights,Window_GF_Toilet,Heating* : strategy = everyChange, everyMinute, restoreOnStartup

// let's only store temperature values in rrd
Temperatuur*, Weer*: strategy = everyChange, restoreOnStartup

}

My my.openhab contents:
Strategies {
default = everyChange
}
Items {

  • : strategy = everyChange
    }

Any idea what could be wrong here?

2

To have a reliable rrd4j persistence you should use “everyMinute”, not “everyChange”. everyChange works sometimes, but not reliable, everyMinute works always …

BTW, I had the same problem when I added my.openhab persistence, after two or three days the problems with rrd4j were gone (without doing anything).

Good luck.

3

The reason for this is that rrd MUST get data within the period that it is storing to disk. In OH, there are fixed periods used for the RRD store - the shortest being 60 seconds. So, if no data is received in a 60 second time period, then RRD will store no data. To ensure data is always recevied within this period, you need to use everyMinute.

Chris

1 Like
4

Thanks for clarification!
I’ve read a lot of times in different forums we should (must) use everyMinute, but there was never an explanation.

Regards

5

Thanks Chris, I changed it to everyMinute, and I see the charts appearing!

6

I have the same problem: rrd4j does not seem to start if myopenhab is present. I work around it this way for now:

  1. remove myopenhab jar from the addons
  2. start openhab
  3. put myopenhab jar back into the addons

A bit painful. Anyone else noticed this ?

I have my config set to every minute, and once it starts, it works fine with graph and all.