I am not sure about the reasons. What you can do is to backup your /opt/trains/data folder periodically (preferably stopping the docker compose before it). Another possibility is to configure your elasticsearch to run as a cluster with 2 or more nodes on the same or different machine. This will allow elastic to replicate your indices to other nodes.

AppetizingMouse58 Great, Thanks so much! You have done a great work.
Another question, how to configure elasticsearch to run as a cluster with 2 or more nodes on the same or different machine 😅

Setting up an elastic cluster requires some devops. You can search for "setup elasticsearch 7 cluster" in the internet and there are some tutorials there. Stopping your docker-compose once in a certain period of time and backing up the /opt/trains/data folder is more straightforward and it would backup also the data that we store in mongodb.

AppetizingMouse58 Ok , i see, thanks!