Currently, the settings $www_root and $data_root are made up of static data (coming from this Git repository), pre-compiled data for each site (Lang_.pm), and ProductOpener's own data (.sto files for products, users, product images, …). For more advanced deployment scenarios, it could be interesting to have an option to split those up in configuration, so that those files could be placed on different volumes without having to place a lot of symlinks between otherwise unrelated volumes.