If I understood correctly, a full but pruned node would need all the blocks + the recent state of each account (and smart contract)?
Yesterday Dec 6th 2017 the number of Ethereum accounts grew to 13.4 million. Based on your article, the size of the chaindata of a pruned Ethereum node is now, depending on the mode, somewhere between 25 and 40 GB?
As more and more apps meant for global use rely on users to have cryptocurrencies and tokens, the number of Ethereum accounts can start to approach that of Internet users in general.
How big even the pruned node will grow if we have like 1 billion plus accounts? Proportional growth from 35 GB / 13.4M accounts node size would give 2.6 TB node size.
Not trying to invoke FUD, just asking?
Hey, thanks for reading it! Without running the numbers, I want to say: it's not impossible. I am just highlighting that we are far away from this and this is not happening soon.
There are a lot of proposals for scalability, I don't really have an overview, and also I do not feel technically qualified to discuss them currently. But regarding the state size, or let's say, state bloat, you might want to read about state-cleaning or dust-cleaning. There are proposals to just purge entries from the state which are provable non-recoverable accounts (i.e., balance smaller lowest possible transaction fee).
The good thing, we still have time, in that regard, to discuss proposals and eventually implement them.
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