Persistence storage size settings

Hi All,

I have configured rrd4j for my default persistence settings in OH3 and all my items are being logged against for analysis.
Not sure how the storage settings work for persistence. Will data continue to be logged for all my items until the disk fills up? Is there an upper limit setting? If so, is the data logged against a sliding window?


No, that’s why rrd4j was chosen as the default persistence database. The name stands for “round robin database for Java”.

The way it works is it saves each supported Item’s state to the database on every update and once per minute. However, when the data becomes 24 hours old, every ten values is replaced with one entry, the average of those ten values. And as it gets older the data is decimated again and again. By the time the data gets years old there might only be one entry per day or less.

On top of that I believe there is a hard limit to the size that the database can grow and it’s not that big.

Is there more info about the persistence settings in OH3? I’ve now everything in influxdb. If I use the same item names, will it continue to work and can I use the nice new graphs?
Can I migrate the data of influx to rrd4j? Is it also possible to keep ALL data for some items?

Thanks @rlkoshak. I appreciate the explanation.

Not really. Your questions are out of scope for openHAB. Dig into the documentation for rrd4j and find out, then contribute your report back to the openHAB community here.

There was documentation for rrd4j in OH2 and the new version in OH3 will also have it ( for OH3 see the preview Here). Reading that you will see that @rlkoshaks explanation gives a “possible” setup only😉. Additionally this database will NEVER grow unless you change the setup, it starts with its final size!

It is possible to tweak the setup of rrd4j to not consolidate data (i.e. keep all stored samples), HOWEVER you have to set the maximum number of samples at startup!