The backup occurs immediately after the file is saved. There is a backup service running where you specify the folders to check for changes but you cant specify how often to check them. So far its working fine. The synology software is highly non-intuitive because it uses a lot of different terms for the same thing. It also told me I MUST setup folders before it could back up which I did. However when it started the backup software created its own folders for which I could not change the name. The folders it told me I had to create cant be removed, or I have not found how to yet. Notice the software says Cloud Station Backup. This is not cloud unless you consider home storage to be cloud. There is a cloud component where the files backed up on the NAS are then uploaded to an actual cloud server but I have not configured that yet and it costs money. Thats another thing that I dont like. The synology software is a constant nag to buy add on services. It was not clear to me during setup if I was using the local device I just bought or remote cloud paid service.