The Ethereum (ETH) blockchain is not yet four years old, and it is already next to impossible to synchronize a full node containing the complete history of the blockchain. The difficulty of synchronizing nodes has been talked about for months now and even specialized paid node operators are having trouble.
This also means that the immutable-state database of all Ethereum transactions may, in fact, be lost, due to the heavy requirements of keeping a full node. This fact may not be noticed by regular users, although for years synchronizing even a full wallet with a pruned blockchain has taken hours. But to store the complete history of Ethereum is a gigantic task.
Currently, even a full synchronization of the Ethereum blockchain does not contain the entire history. Recently, BlockCypher, a provider of blockchain-related services, attempted to run a node with the entire history, and discovered that no other actor on the network ran the node.
BlockCyper contacted Vitalik Buterin, but he stated that he knew of no entity that ran the complete node with the full history. Not even the Ethereum foundation took the task of running such a node. This also means that in the rare event of a chain reorg, where malicious mining alters the history of the distributed ledger, BlockCyper may be the only entity to hold the entire history of the blockchain for verification.
This, in effect, wipes the opportunity for reliable feedback in case of reorgs, hacks, or other exploits. In the case of audits and blockchain searches, some entities may have to rely on archival states supplied by third parties. Previously, the general understanding was that the Ethereum network had three or four full nodes, on which most other entities relied. However, some of the leading actors within the ecosystem have abandoned the task:
Other networks face a similar problem. The much newer EOS network also does not have its full state stored on multiple locations, with talks of just two block producers storing the complete blockchain history.
The complete blockchain history is needed if there is a requirement to track the state of an account at any given block height. Hypothetically, a reorg could alter that state, with only very limited recourse to the accepted valid state.
The news of troubles with Ethereum nodes barely affected the price, as ETH markets remain mostly speculative. ETH price remained almost unchanged at $133.90 as of 8:20 UTC on Tuesday.