Introduction

The emergence of the Data Availability (DA) layer is due to increased demand for scalability and higher data availability in blockchain technology. The development of the DA layer is an important stage in the evolution of blockchain technology, similar to the specialization of labor in human society. Today, modular public chains have become the standard mode, with the DA layer being one of the most fiercely competitive areas.

Modularity is the Foundation of DA

Modularity propels the development of the DA field and lays the foundation for its implementation. In the Ethereum ecosystem, horizontal modularity is seen in sharding technology. Vertical modularity is seen in the layered structure where Rollups manage transactions, and the mainnet oversees DA and consensus mechanisms.

Modularity’s core concept is to separate the system’s functions into different levels and make them interchangeable. This allows for customization of specific use cases or vertical domains, increasing flexibility and scalability.

Rollup achieves efficient transaction processing by batching transactions off-chain and then periodically validating them on-chain.

Source: celestia

The design of Rollup varies depending on the state verification mechanism and the location where the state data is published. From the perspective of the Ethereum ecosystem:

• Validity Rollups: Data and validation status are obtained on L1 (validity proof).
• Optimistic Rollups: Data and validation status are also carried out on L1 (fraud proof).
• Validiums: Data is processed off-chain, and validation status is carried out on L1 (validity proof).
• Optimiums: Data is processed off-chain, and validation status is carried out on L1 (fraud proof).

Different design choices offer flexible solutions for various scenarios and needs, opening more avenues for the growth of the DA field.

What is DA?

Data Availability (DA) refers to the process where Layer 2 packs state data, including transactions, into the Layer 1 mainnet. After verification and consensus, it is published on the L1 main net, providing verification support for each L2.

Data integrity and availability are essential for modular blockchains and Rollup networks. The network can only assure its decentralization and security when the data is available and can be used. Thus, data availability plays a vital role in ensuring the normal operation and security of blockchain networks.

DA Methods and Cost Analysis

Data Availability Method Analysis

Data Availability (DA) is a major component of the cost of Rollup. Currently, Ethereum’s Layer2’s data availability mainly uses three methods: Calldata, DAC (Data Availability Committees), and “Blob.”

In the Calldata method, Layer2 solutions like Arbitrum or Optimism directly release transaction data as calldata into Ethereum’s blocks, achieving high censorship resistance. Ethereum prices data calls, computation, and storage uniformly under Gas, which is also one of the main costs incurred by Rollup on Ethereum.

To improve efficiency, the EIP-4844 upgrade introduced a new transaction type “Blob,” moving the data content of Layer2 transactions to a new temporary “Blob” for storage. Since “Blob” is an external temporary storage and doesn’t store Layer2 transaction data in Layer1, it greatly reduces storage costs. This approach benefits Layer2 by lowering storage costs and increasing speed.

On the other hand, the DAC method offers a much higher throughput. However, it requires users to trust a small node or group of validators to prevent malicious data withholding. DAC introduces a significant trust assumption into L2, including re-staking solutions. This forces DAC to depend on reputation, governance mechanisms, or token voting to discourage data non-publishing behavior. Therefore, when using external DA, reliance on DAC may be necessary.

Cost Analysis of Data Availability

Data Availability (DA) is often a critical component in the design of an entire blockchain system. Especially in the case of monolithic blockchains like Ethereum, where block space utilization is high, block size becomes a key limiting factor in its development. Over the years, Ethereum has been actively addressing scalability issues and exploring various layer-2 scaling solutions.

The Data Availability (DA) layer is a core component of modular architecture used to reduce costs and expand the capabilities of the blockchain. Its primary task is to ensure that data on-chain is accessible to all network participants. Traditionally, each node had to download all transaction data to verify data availability, which was inefficient and costly. This situation limits the scalability of the blockchain because as block size increases, the amount of data required for validation also increases linearly. Consequently, end-users may incur high data availability costs, consuming up to 90% of their transactions on Rollup. Modular data availability layers are considered a potential solution to reduce DA costs, capable of lowering costs by up to 99%.

Over the past five months, Rollups on Ethereum have collectively spent around 10,000 ETH per month on data availability.

Assuming an average of 10,000 ETH per month, priced at $3,000 each, this equates to a DA cost of $30 million.

Source: dune

Comparison of Core DA Layer Solutions

Avail, EigenDA, and Celestia are the main players in the DA ecosystem, but they adopt slightly different approaches regarding infrastructure stack, consensus mechanism, security, and branding.

Technical Architecture

Unlike Celestia and Avail, EigenDA is just a set of smart contracts relying on Ethereum. Avail, Ethereum, and EigenDA use KZG commitments, while Celestia uses fraud proofs to confirm the correctness of block encoding. KZG commitments provide a strict method for data availability, but it increases the computational overhead for miners. Celestia’s fraud proofs, on the other hand, assume data can be implicitly obtained, but there is a waiting period for fraud-proof disputes before nodes can confirm that the block has been accurately encoded. Both KZG proofs and fraud proofs are undergoing rapid technological advancements.

Consensus Mechanism

Celestia uses the Tendermint consensus mechanism, which requires peer-to-peer network communication. On the other hand, EigenDA decouples DA from the consensus and broadcasts directly. This allows data block propagation to be unrestricted by consensus protocol and P2P network throughput, resulting in faster network communication and shorter confirmation times.

However, EigenDA depends on the Ethereum mainnet’s EigenDA contract to conclude verification. Regarding final block confirmation time, Celestia is significantly faster, requiring only 15 seconds compared to EigenDA’s 12 minutes.

Avail utilizes the BABE + GRANDPA consensus mechanism, which is inherited from Polkadot’s SDK. It uses Nominated Proof of Stake and BABE rules to decide the next block. Despite its block confirmation time being slower than Tendermint, Avail verifies transaction accuracy faster than Celestia, thanks to using KZG commitments for validity proofs.

Data Availability Assurance

Celestia employs fraud proofs to ensure data availability, while EigenDA utilizes KZG commitments for validity proofs, offering faster speeds but requiring additional computational overhead. Celestia’s active validator set stores the entire dataset, whereas EigenDA optimizes storage for a small portion of data on each node to ensure data reconstruction. Avail leverages KZG polynomial commitments to reduce memory, bandwidth, and storage requirements, facilitating an efficient validation process.

Data Availability Sampling (DAS)

Data Availability Sampling is a technology that allows light nodes to download only a portion of block data to verify data availability. This technology provides security for light nodes, enabling them to verify invalid blocks (limited to data availability and consensus aspects) while also allowing blockchain to expand data availability without the need for corresponding increases in node requirements.

Celestia and Avail will both support data availability sampling light nodes upon release. This means they can safely increase the block size by accommodating more light nodes while maintaining low user requirements to validate the chain.

Although EigenLayer announces no official plans regarding DAS, there are indications that DAS may become an alternative solution.

Security

Compared to traditional full nodes, traditional light clients have weaker security because they only validate block headers. Light clients cannot detect whether a dishonest majority of miners generates invalid blocks. However, light nodes with data availability sampling capabilities have improved security because they can verify whether invalid blocks are produced.

Celestia enhances its security by conducting data availability sampling, with its security guaranteed by the value of its network. The higher the network value of Celestia, the higher the cost attackers have to bear, and the smaller the probability of a successful attack.

In contrast, EigenDA does not perform data availability sampling but relies on a majority of honest heavyweight nodes, with its security being a part of Ethereum’s security. The security of EigenDA is influenced by the value of re-staked assets in the EigenDA network and the proportion of node operators in the Ethereum mainnet.

Avail incorporates data availability sampling, furnishing it with an efficient and reliable backup mechanism that maintains data availability even during failures. Furthermore, Avail uses Polkadot’s Nominated Proof of Stake (NPoS), accommodating up to 1000 validator nodes. NPoS also has an effective reward distribution mechanism, helping to decrease the risk of stake centralization.

Brand and Objectives

From a branding perspective, EigenDA is a product that aligns closely with Ethereum. EigenDA’s brand aim is to become a data availability layer centered around ETH, distinct from other DAs, it aims to serve the Ethereum ecosystem. Avail, on the other hand, is committed to aggregating all the ordered transaction data from all chains, becoming the coordination center for all web3. Celestia’s ecosystem includes RaaS providers, shared sequencers, cross-chain infrastructure, etc., covering ecosystems like Ethereum, Ethereum rollups, Cosmos, and Osmosis.

Summary

Celestia is recognized for its low Data Availability (DA) costs and high throughput performance. This makes it appealing to small and medium-sized Layer 2 (L2) and application chains, enabling them to save on high DA costs. The saved assets can then be used to distribute revenue profits and promote their ecosystems and liquidity growth.

On the other hand, EigenDA’s competitive edge is rooted in its close ties with Ethereum’s security and orthodoxy. In the short to medium term, large-scale L2s may find EigenDA a more rational choice due to Ethereum’s high DA costs.

Avail employs advanced technology allowing light clients to verify data integrity without the need to download the entire blockchain. This makes blockchain technology more accessible to users. Since separating from Polygon, Avail has sought new partnerships with a variety of entities, showcasing its versatility across multiple application scenarios.

The image below shows a comparison of various DA layers with Avail.

Source: Avail Blog 2024.4.20

Conclusion

Currently, Rollups have emerged as the primary path forward for Ethereum, which means that Ethereum has handed over the definition of Layer2 to the market. This seemingly developing trend contains various forms of competition. In general, the continuous emergence of related DA solutions such as Celestia has indeed weakened Ethereum’s competitiveness in the DA field to a certain extent.

The charm of modularity lies in the decoupling between its components. This allows each layer of innovation to build upon one another, and optimization of each module can enhance the performance of others. In the future, the development process of modularity might offer a wealth of competitive choices for both developers and users.