yeah, I have the same question. In fact, I wonder if this decomposed fs feature is something similar to what Google Photos uses “under the hood” to achieve such awesome cloud-based random-access performance. Anyway, I just stood up my own instance of oCIS using docker to play around and it looks like the idea of an “external storage” option has not been contemplated.
I’d like to keep my file structure organization as-is, too – the existing files are local to the host that is serving the oCIS docker container but there are other applications that access the same files structure on the host. So, using something that will completely change the file structure is a non-starter for me. I Googled around for a while trying to find out if there’s a way to point oCIS at an existing file structure (like external storage in OwnCloud and NextCloud) and wound up here. 