I don't understand how a blockchain that includes code + data can be decentralized, ie duplicated amongst all nodes. Doesn't this one store (The Ethereum Blockchain) can potentially take petabytes of data if it's used by the entire world?
Depending on how the chain is synced (tracing on, pruning archive, etc.) it currently takes between 5-10 or up to say 20-25 gig. This after two and half years. Obviously this doesn't scale. The best proposed solution so far is called
Sharding which divides the chain among subsets of the nodes.
You can read about sharding here: https://github.com/ethereum/wiki/wiki/Sharding-FAQ among other places.
This appears to pose its own problems. If the virtue of the distributed ledger is that all information is "forever" and accessible, doesn't bifurcation, or multiple divisions of that information eventually slow down the process of information retrieval? The "safety" in Blockchain is the virtually immediate duplication of all new additions to the block across the system. If some of the nodes are non-compliant in maintaining the latest technology, and less than diligent in their security, isn't it possible to lose information owing to human error? Plus, how will the ever-increasing sizes of blocks be impacted by normal network bottlenecks, outages (such as those created by DDoS attacks or power outages), and potential "cyberterrorism" undertaken by organized entities?
No one seems to be discussing the size, transmission, or operator compliance issues all that much. The cryptography is part of an astounding technology, and the concept appears to have excellent potential. But, at what point will the obvious inherent weaknesses of the technology be discussed more openly, and the adoption of specific standards and regulations be imposed? The "Libertarian" model of "effectiveness dictating form" doesn't seem to have much historical validation in ANY context, and for Cryptos to ultimately supplement or replace Fiat Currencies it really does seem logical to assume that some sort of governmental or international agreements will need to be reached and implemented. Just curious to hear how these issues might be resolved.