THere is a lot of confusion here and a bot of speculation being seen as hard facts. So here is a few points.
- We calculate and test everything. So if 4 is enough then it will be the case, right now it’s over 8 actually (it is whole sections so can be 20 or more copies).
It may decrease to 4 I think it will, but and this is very important, only if we can prove that is secure. (tl;dr I will alway guess forward but he team forces testing and certainly where possible on these guesses). that’s innovation, what seems mental like going to mars may in fact not be mental given enough thought, 4 copies may be less mental than terraforming another planet )
Then the actual issue of catastrophic events.Here is my take on this without too much thinking of the edge cases.
- The network should contain the knowledge of all humanity and with luck it will.
- The addition of knowledge is extremely important (theories -> laws etc.)
- The manipulation of data is very important (mutation of knowledge, transactions etc.)
So we have immutable and mutable data as we all know. Immutable data can be stored anywhere and secured, Here archive nodes can help. So on these archive nodes, what would they hold and how much would they hold? We go back to my guesses, here I claim that storage is becoming cheaper and more capable very quickly, I expect to be able to store the worlds data on a single device sometime not far away. Until then I expect significant increases in small devices, particularly IOT types.
Then mutable data, now that is more difficult, but we have data chains where we can show a version was secured on the network at some stage, but we cannot be sure if it is the latest version. for that we need more info, if it becomes available. So silo’s can hold this as well, it may or may not be the latest data.
However as the network restarts, even with new hardware (if it was a huge emp type catastrophe) then these silo’s can connect, compare their data, data chains and find the latest known version of any data. Even if a single peer can come on line it can show a later version (this is powerful) that the restarting network can accept.
Anyway, this is a snippet of how such autonomous networks can restart after catastrophe, it is not about losing a chunk, it’s about keeping them all and away they can be re-inserted on the network. So that is data chain + some data that fits the chain. It goes a lot deeper, but anyway I think it is pretty clear to be confident this is a solved problem here and post launch it is not an impossible thing to solve, it just needs some thought as to exactly what the fundamentals of the data types and proofs of valid data are, where they were stored or held is then a simpler issue.
tl;dr archive nodes will not be difficult, may never be needed but may be the norm depending on advances in storage tech.