Is it possible to sync 2 servers, so one server can be used when abroad or one server come down while keeping both in sync?
Hi Bchesneau, welcome to the Seafile Community Forum!
Seafile Professional supports clustering and can also handle a real-time backup server. I am not sure which setup is closer to what you are looking for, but I think the latter sounds about right.
The real-time backup server is synced continuously with the production server. It kicks in when the production server goes down. But they cannot be used at the same time. More on RT backup server here.