@dirvine, I see a major problem with non-persistent vaults. The idea of the SAFE Network is not only privacy and security, but also data security. What you are essentially setting up with non-persistent vaults is a large networked RAM storage, am I right? The only problem with ram is that if the power goes out, then you lose the data. Your argument is probably that if a machine goes off, then one of the other 4 machines on the network that are storing the chunks will copy the data. This sounds good, but then to attack the safe network, all you have to do is cause a great many machines to reboot/shutdown at the same time, or just close the SAFE program. This means that the network is not secured against a massive power outage, if the entire network (or most of it) was shut down, then all of the data would be lost. This seems less robust than with persistent vaults, where if the entire network turned off, then when it rebooted, the network would be fine. A network shutdown could be caused by anything such as a country wide power outage, windows automatic updates, a large-scale virus, or even something human related such as Earth day!
That’s one problem on a large scale, but what about something a little more commonplace, if a lot of people turned off their computers for Earth day, then that day, the total storage space the SAFE Network has available shrinks by maybe 20%. But what if the network is almost filled to capacity? Where does the data go? I think you absolutely need persistent vaults, not just non-persistent vaults. If I’m storing data, and something like this happens, I don’t want /any/ of my data to be lost. And if some data is not stored persistently, then there is a much greater chance that my data would be lost by bad luck or circumstance. I propose that you have both persistent and non-persistent vaults storing data. So if my data is stored 4 times, there is at least one copy stored on a persistent vault.