Rpi for Media Storage
I use a RPI3 running Open Media Vault for storing all my media
Open Media Vault does a great job of abstracting disk and file paths so that if you do need to swap disks, the operation should be painless.
I have 2 2TB disks attached. One acting as a back - backups managed through OMV.
OMV has a simple web interface which handles the bulk of the management tasks.
For actually playing the media I use cheap android TV boxes re-flashed to use openelec (another kodi distribution). They are all set up to use a shared library which is stored in a mySQL database on the OMV server. What this means is that I can watch half a film in the living room then seemlessly resume watching in the bedroom.
I found the RPI3 to be unreliable when playing HD sources.