First of all, thanks the OwcCloud team for this great application.
I'm running: ownCloud 9.1.1 (stable) on a VirtualBox CentOS 7 VM, as I do for all my servers/applications/appliances.
The first thing I had to solve was how to store my files on my NAS' cif.
The only way I managed to do that was to create a share on my NAS owned by my http user/group, and mount the owncloud data directory to it after the installation and before run it for the first time to finish the configuration.
I must say it works great as it did as a plugin in my NAS, but give me full control, back-up/snapshot capabilities, freedom to upgrade with the OC releases, etc.
My question is if there is another way to do that besides what I've described above?