Hi AstonishingSeaturtle47 ,
As specified in section #6 in the Trains-Server launching instructions ( https://github.com/allegroai/trains-server/blob/master/docs/install_linux_mac.md#launching-the-trains-server-docker-in-linux-or-macos ), the data folder contains data for elastic, redis, mongodb and the fileserver. Of those, the fileserver data is totally safe to copy while the system it up. As for elastic, redis and mongodb, copying the files while the system is up is not considered safe - you can try it, but I wouldn't recommend it (any activity while you do it might cause you to end up with corrupted data).