I’ll provide a couple of helpful links because this topic has been discussed at nauseum, but I understand that sometimes it’s hard to find links to good documentation!
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Main persistence WIki (read first)
https://github.com/openhab/openhab/wiki/Persistence -
more advanced concepts posted by @rlkoshak
Design Pattern: Group Based Persistence
Once you’ve looked at these resources and have specific questions feel free to post and there are many people here that will be able to help!