In order to make the decision easier for some of you, I would like to tell you about my experiences with the migration from OH2.5.11 to OH3 stable.
You have to take into account that I have been working in IT for 30 years and as a result I certainly have a technical understanding, but my programming knowledge stopped 15 years ago.
Currently openhab runs on a Raspberry 4 with 4 GB Ram (based on the Raspberry original image). Instead of a SD - card I switched to a SSD.M2 about 3 months ago, which is first of all much faster and secondly more stable (with SSD cards there are often errors because they are not designed for constant writing/reading).
Currently there are about 150 Things and 430 Items. The following components are to be served:
HomeMatic (Cul for intertechno)
RFXCom (also for intertechno and some nonames)
HUE (Incl. Tradfri Devices)
Harmony (3 Hubs)
Amazon (6 Alexas)
Gardena (mower and sensor)
Telekom - Magenta
Home Connect (NEFF)
FritzBox (TR064 and AVM Fritzbox Binding)
Samsung (div. TVs)
The Network-Binding for monitoring the network and the Exec for executing scripts, remote Pushover for sending messages. Furthermore the persistence based on mysql.
Backup ! SSD image backup as well as config backup - furthermore I allowed myself the luxury to clone the current OH2.5.11 installation on a 2nd SSD.M2 to go back quickly.
OH2 service stopped.
First installed JAVA 11 and followed the instructions from Kai (Releases · openhab/openhab-distro · GitHub).
Restart Raspberry and wait - I think that some conversions are connected with the first start - so to be on the safe side give it some time first.
What I want to say here is that I had to restore the backup after the first change and the first attempts because some installation steps and settings were wrong and I want to have a “clean” system. Therefore, you really can not skip the backup!
The new UI - first impressions
At first glance it looks tidy and clear, in parts you will find again what you knew from 2.5, much is new. The arrangement is a bit hard to get used to because it does not always correspond to the logical order - my mistake was not to read the headings.
On the 2nd look you realize that many settings are completely different and you have to bring more technical understanding than in OH2 - but that may also be due to the fact that the philosophy must first be understood which is now more clearly anchored in the interface.
One point for me is the semantics - here I clearly have to deal with in detail. In addition wr come however also to a current problem with OH3 - that are the descriptions and examples. Here is not yet so much there but that will certainly change in the coming months.
Genrell as experience I can say that everything you do in the UI takes significantly longer. I don’t always find it intuitive and it takes time to find the places where you want to go. If you limit yourself to Things and Items it goes faster.
Technical adjustments / problems
Essentially, the changeover was quite safe. But you have to remember that it is the first release and there are bugs for sure. It is also very important to check the log, track the events. Also the bindings should be checked. Various ones are not installed automatically - I guess because they have changed incompatible and manual interventions are necessary.
I will only go into the problems, HUE, Homematic, TP-Link, … ran without problems.
First I removed paper, mysql, fritzboxtr0641, restdocs from the ADDON - file. These are tried to load, but no longer exist.
**2020-12-30 16:25:33.259 [WARN ] [core.karaf.internal.FeatureInstaller] - The binding add-on 'fritzboxtr0641' does not exist - ignoring it.** **2020-12-30 16:25:33.338 [WARN ] [core.karaf.internal.FeatureInstaller] - The persistence add-on 'mysql' does not exist - ignoring it.** **2020-12-30 16:25:33.377 [WARN ] [core.karaf.internal.FeatureInstaller] - The ui add-on 'restdocs' does not exist - ignoring it.** **2020-12-30 16:25:33.380 [WARN ] [core.karaf.internal.FeatureInstaller] - The ui add-on 'paper' does not exist - ignoring it.**
After that the JDBC MySQL Binding had to be installed for the Persistance. The next error was the length of the text fields.
2020-12-30 17:23:07.678 [ERROR] [org.knowm.yank.Yank ] - Error in SQL query!!! java.sql.SQLException: Table 'openhab3.Item135' doesn't exist Query: INSERT INTO Item135 (TIME, VALUE) VALUES( NOW(), ? ) ON DUPLICATE KEY UPDATE VALUE= ? Parameters: [DISABLE_ACOUSTIC_SIGNAL, DISABLE_ACOUSTIC_SIGNAL]
Missing records created manually and added to jdbc.cfg (service folder)
sqltype.STRING = VARCHAR(16000)
The problem with the TR064 binding could have tipped the switch - here the presence detection is done via the MAC addresses by means of the connected mobiles. It took me a while and the help of the community to find out that - if you have more than one MAC - you have to write them in a second line and not separated by comma or … separated. There was also a fix for this. Many thanks to Jan who took care of this in time.
A little bit more work was the adjustment of the pushover messages. After I had found different contributions also the syntax was clear. Since I have many points where messages are sent I had to touch more or less all rules.
I did not get Gardena running (wintertime no problem) - but the binding was also completely rewritten. The Home Connect (manually installable binding) is undefined in OH3 in the behavior - sometimes something works, some not at all. Here is also still work on the part of the developer (many thanks to Jonas !) necessary.
On the whole, the switch was worth it. Some things are still not completely solved, but for me there are no showstoppers. But there has to be an update soon which fixes the basic problems - also concerning the runtime. Here the system is super fast, but it gets slower with time - maybe the JAVA settings have to be changed.
As with OH2 I restart the service every morning - that fits because I always make a backup (database and config).
I can only advise this to everyone - with SD card it happened that the system stopped and after a restart all Things ud Items were gone. You are thankful if you have a backup ! You can’t say that often enough.
Topic Raspberry, here I think OH3 comes to the limits for PI3 systems. Memory requirements are higher, CPU performance is not a problem in my opinion.
HTOP on Raspberry 4:
For Raspberry PI 4 system I can only recommend everyone to switch to a SSD.M2 USB3. There are several tutorials on the net. The factor speed is felt factor 10 or more. The start of the system is very fast compared to SD card. Unfortunately, there are only M2 cards from 240 GB (about 40 € + 20-30 € for housing) of which I use only 32 GB. The rest is reserve if you need a 2nd drive. In any case more stable and durable.
I hope that my report may help some to make a decision for themselves whether they switch, how they switch or whether they do not switch to OH3.
Since my English is not perfect I have translated this by deepl - hope it fits