I was a huge fan of Wuala, and was very disappointed when they got bought and then shut down. My understanding is they always stored a central copy of everythin

I was a huge fan of Wuala, and was very disappointed when they got bought and then shut down. My understanding is they always stored a central copy of everything on their servers to 100% guarantee availability. The P2P copies merely helped with bandwidth. I think their main innovation is the cryptree data structure for access control. We use a more advanced version of that in Peergos[1]. [1] https://github.com/peergos/peergos https://github.com/peergos/peergos