Node Architecture
Ethereum nodes come in three types — full nodes (store recent state and validate all blocks), archive nodes (store complete historical state for every block), and light nodes (verify block headers only) — each representing a different tradeoff between storage requirements and query capabilities.
Post-Merge, an Ethereum node runs two clients: an execution client (Geth, Nethermind, Besu, Erigon) handling transactions and EVM execution, and a consensus client (Prysm, Lighthouse, Teku, Lodestar) handling PoS consensus and validator duties. Full nodes store the current state plus recent blocks (~1TB SSD), validate all transactions, and serve RPC requests. Archive nodes store historical state at every block height (~14TB+), enabling queries like "what was this account's balance at block 15,000,000?" Essential for block explorers and analytics. Light nodes (Helios, Nimbus) only verify block headers and use Merkle proofs to validate specific state, requiring minimal storage (~1GB). They trust that the consensus chain is valid but can verify any specific claim against it.
Tradeoffs
Strengths
- Modular client architecture (execution + consensus) enables independent development and upgrades
- Multiple client implementations provide resilience against single-implementation bugs
- Light clients enable verification without full node hardware requirements
- Snap sync dramatically reduces time to get a node operational
Weaknesses
- Full node storage requirements (~1TB) are non-trivial and growing
- Archive nodes require expensive hardware (14TB+ fast SSD)
- Running two clients adds operational complexity
- State growth threatens long-term node decentralization
Likely Follow-Up Questions
- What is the difference between a full node and an archive node in practice?
- Why does Ethereum require two separate clients (execution + consensus)?
- How do Verkle trees improve upon Merkle Patricia tries?
- What are the risks of RPC provider centralization?
- How does snap sync work and why is it faster than full sync?
- What is client diversity and why does it matter for network security?
Related Concepts
Source: editorial — Synthesized from Ethereum client documentation, devp2p specifications, and Ethereum roadmap materials