The 1.x Files: a fast-sync

The 1.x Files: A Fast Sync

The Problem

Ethereum's growth has led to a multitude of issues, including increasing storage requirements, slower transaction processing, and a larger state that affects network performance. Unlike a security vulnerability or major design flaw, there is no single pressing issue that can be identified and addressed. Instead, the problems arise from small, subtle degradations of performance and diminishing network health as a result of natural chain growth.

Chain Storage

Storage requirements are a significant concern for full nodes, with the current storage requirements being around 219 GB for a "normal" full node in both parity and geth, and growing by 10-15 GB every month. While this may not be a significant issue from an absolute cost-of-storage perspective, the marginal cost of spinning up new full nodes is a concern. Increasing storage requirements and sync times lead to fewer full nodes, which leads to even longer syncing times and fewer nodes still.

Block Size and Transaction Throughput

Ethereum does not explicitly limit the size of a block by memory, but enforces the block size through a gas limit. The gas limit in Ethereum effectively caps the number of transactions that can be included in a block, and is decided collectively by miners, with a vote to increase or decrease the gas limit dynamically. Recently, miners collectively agreed to increase the block gas limit to around 10 million gas units, making each block about 25% larger than it had been since January 2018.

State Size and Network Performance

Ethereum is a state machine that moves forward one step with each block. At any given moment, the complete "state" of Ethereum comprises the collective memories of all smart contracts deployed and running in the EVM, as well as the current status of all accounts and balances. The total size of state currently weighs in on the order of 50GB, and is expected to grow by an order of magnitude in the years to come.

Potential Solutions

Several proposals have been discussed to address the issues with Ethereum's growth, including:

• Modest optimizations and mitigations, such as more aggressive pruning, block pre-announcement, and state caching.
• Big, hard-forking changes, such as opcode re-pricing and ETH lockups, state rent, and "eviction".

The New Direction: Stateless Clients

If the size of state is causing the biggest problems for network health, the ultimate solution would be to do away with the need for state altogether. In a nutshell, a stateless client makes use of a block witness, which proves the validity of a given state change against the previous state. That is to say, rather than computing a complete state with each new block, clients simply compute the changes to state for a new block, and then prove that those changes are consistent with the previous block.

Conclusion

Ethereum's growth has led to a multitude of issues, including increasing storage requirements, slower transaction processing, and a larger state that affects network performance. While several proposals have been discussed to address these issues, the ultimate solution may be to move towards a stateless or semi-stateless paradigm. This would require significant changes to the Ethereum protocol, but could potentially lead to a more scalable and efficient network.

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Source: https://blog.ethereum.org/en/2019/12/10/eth1x-files-fast-sync