Is there a solution/recommended usage policy for site proxying?

My owncloud is a family (well also brothers, cousins, parents,...) cloud with a lot of big datas (pictures) more than tiny files.

I am using a dedicated server (I just do not want to use my bandwidth for this).

In my own house, we are syncing 2 different Computers (and apps). So when I come back from Holiday, I save 300 Pictures which are send to the server then come back to the other computer, using my (and from the server) bandwidth twice. I thought that maybe I could install a site version (on a rasperry py), which would be used as a proxy, preserving the network usage. The federated cloud storage thing could do the job (as a workaround), but I guess it would brings a lot of complexity (especially for the Laptop, when not at home).

Do you have any suggestion / remark about my use case? Any help is appreciated.

There is no master-slave or syncing function between servers. You could somehow try to sync the file-systems and keep the databases in sync. I doubt that there is a fool-proof version of this and for some simultaneous access you could easily run into problems.

You could use owncloud with external storage on a local folder and then sync this local folder on your server with btsync/syncthing or other sync solutions that provide client-to-client transfer as well (such solutions are used).

Related feature request which could be interesting for you: