I lost a node (disk failure). Can I restore the node from a backup, synthing config, index and all files and then connect the node with the same nodename and ID?
The state of the files and the index-files in the restored node are older than what the other nodes for the restored node have. Would this create a problem?
After sync of the restored node, will I have all the files changed to the current state in the other nodes?
You can restore the files, the config with key files, etc. but I wouldn’t restore the database, especially if you’re unsure of its state (as it could have got corrupted during the disk failure).
What I always do in such a case is to initially set all folders to “Receive Only” (by editing the config.xml file before starting the application). This will make Syncthing scan the local files, pull remote changes, but it will not push any unwanted local changes to remote devices. After the initial scan and sync have finished, you can check the folders in the Web GUI, and if everything looks correct, change their types to the original ones again.