Written by Avail; Translation: Golden Finance Cryptonaitive
In recent years, the focus on scaling execution capabilities has brought a new wave of adoption to Layer 2. At the same time, faced with the growth challenges posed by limited block space and high costs, more and more players now recognize that a scalable data availability layer is critical to effectively scaling blockchains. They have realized that they need an economic base layer with scalable block space that can support various types of Rollups.
Avail and several other teams are building scalable data availability solutions from the ground up, while others, such as Ethereum, are trying to increase data availability capacity in existing blockchains. Either way, one fact is always there. The base layer developers choose today will define their competitive advantage for years to come.
Avail is part of a growing modular ecosystem dedicated to increasing data availability on the blockchain. Other DA solutions, such as Celestia and EigenDA, are doing similar work. Each solution has chosen a different path on the road to blockchain scalability, including Ethereum, which is currently implementing Proto-Danksharding, also known as EIP-4844, as a springboard to achieve its long-term goal of comprehensive Danksharding.
This article will evaluate the advantages and disadvantages of each solution. We will highlight the different design options, and with the knowledge that this comparison brings, we hope that readers will find the DA layer that best suits them.
Before diving into each category, let’s give some overview:
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Network security
When considering the base layer, the security and resiliency of the network are the first things to consider. Here are the key factors to check the strength of your network.
Consensus mechanism
In the consensus mechanism, there is a basic dilemma between survival and security. Survival ensures that transactions are processed quickly and keeps the network functioning properly, while security ensures that transactions are accurate and secure. Different blockchain systems find the right balance option for their unique use cases.
Avail uses the BABE and GRANDPA consensus mechanisms inherited from the Polkadot SDK. BABE, as a block generation engine, prioritizes survival by coordinating with validators to identify new block generators. GRANDPA as final determinism, it makes it possible to complete the final certainty of all blocks that lead to a particular block at the same time when more than two-thirds of validators sign the chain containing the block. This hybrid ledger makes Avail cyber resilient and makes it resilient to transient network partitions and a large number of node failures.
Avail’s design choices are similar to those used in Ethereum as Casper and LMD GHOST. LMD GHOST is Ethereum’s block generation engine, which relies on probabilistic final certainty similar to BABE, while Casper FFG, like GRANDPA, provides final certainty guarantees.
Celestia’s design choice was to use Tendermint, which allowed it to finalize blocks at the same time as they were generated. However, the trade-off with this choice is that the chain may stop when more than one-third of its operators or validators go down. It is also important to note that block finality does not guarantee data availability. A fraud-proof-based design like Celestia’s means that users need to wait for DA guarantees, even if the block has achieved immediate final certainty.
The Data Availability Board, or DAC, is the entity responsible for providing or certifying data availability. They use cryptographic signatures to indicate that one or a majority of the committee members agree that the data is available. EigenDA is an off-chain DAC that Ethereum validators can opt into. DAC members provide proof of smart contract validation and rely on an independent external service for data sorting.
Decentralization
When considering network security, there are two key factors to consider: the total amount staked and the distribution of that staking. The degree of decentralization, that is, the uniformity of the distribution of the staked amount, directly affects the security of the network. Considering the cost of a potential attack, this is an indicator of how secure the network is. Because an adversary trying to attack the network needs to destroy more nodes to capture the same staking, the attack is more expensive if the stake is evenly distributed across a larger set of validators.
Avail inherits the Nominated Proof of Stake (NPoS) from Polkadot, enabling it to support up to 1,000 validators. NPoS mitigates the risk of centralization due to its staking distribution through its sequential Phragmén method, the multi-winner election method, with efficient reward distribution.
In addition, Avail is the only DA layer that can sample from its Light Client P2P network without relying on full nodes to fetch data in the event of a network outage or bottleneck. This unique capability sets Avail apart from all current and future data availability solutions, provides a robust failover mechanism, and enhances the resiliency of Avail’s data availability network.
! [bQ55EOrxKLi9t7hdoXANmRHdmgW2dPubzQe6dtuI.jpeg] (https://img-cdn.gateio.im/webp-social/moments-40baef27dd-3d4adfd490-dd1a6f-69ad2a.webp “7116199”) Celestia uses Tendermint as its consensus protocol, and its set of validators is up to a few hundred.
Although Ethereum as a whole blockchain has reached the gold standard in terms of security, with more than 900,000 validating nodes, the distribution level of the network is not adequately reflected in terms of quantity.
In contrast, a data availability board typically consists of several nodes responsible for confirming the availability of data to the blockchain.
It is important to note that restaking does not borrow security from Ethereum. Its security depends on the total amount of Ethereum restaked on its platform. In other words, restaking does not do any good for its security, except for the use of a small fraction of the existing staking locked in Ethereum.
As a DAC, Ethereum-based EigenDA aggregates signatures from its full nodes. Its smart contract validation proof cannot provide a similar level of DA assurance for data availability sampling. EigenLayer’s use of restaking, involving locked Ethereum to support its network, has also drawn criticism of multiplexed validators and the risk of overloading Ethereum consensus.
Execution environment overhead
Monolithic blockchains with smart contracts have introduced groundbreaking innovations over the past decade. However, even cutting-edge technologies of the time, such as Ethereum, where data availability, execution, and settlement were merged into one, introduced significant scalability limitations. These restrictions spawned the shift of execution to Layer 2 off-chain and prompted the development of improvement initiatives such as EIP-4844, also known as Proto-danksharding and Danksharding.
Established smart contracts define the state and act as a bridge for rollups. In this approach, Ethereum acts as an authority to verify the accuracy of rollups.
Avail splits execution and settlement from the base layer and enables rollups to publish data directly to Avail. The power of this modular approach lies in the fact that rollups built on it can verify state by using Avail’s P2P light client network, and if used to propagate proof of execution, they have the flexibility to upgrade rollups without having to rely on smart contracts and base layers to define state. This new approach gives developers a base layer that can be scaled with their needs, giving them the option to choose any supported execution layer in terms of settlement.
Celestia takes a similar approach to Avail. The only difference is that its light clients are currently unable to support the network in the event of a full node down.
EigenDA also does not have a fixed settlement layer.
Growth potential
In addition to the security and resiliency of the DA layer, the ability to adapt to the growing demand for rollups and blockchains built on it is critical to their success. Let’s look at some key considerations.
Proof of validity
When discussing proof of validity, it is crucial to understand the trade-off between proof of fraud and proof of validity in the DA layer. The KZG promise used by Avail is a type of validity proof used to ensure the validity of DA, which reduces memory, bandwidth, and storage requirements, and provides simplicity, meaning that the size of the proof is fixed and not affected by polynomial degrees. This makes KZG Promise a perfect fit for zero-knowledge-based blockchains where efficiency, privacy, and scalability are critical.
In addition, compared to proof of fraud, Avail’s light clients can quickly access and sample data, ensure correct block encoding after new blocks are finalized, and provide data availability guarantees without waiting for the end of the challenge period. The combination of KZG promise and Avail’s light client accelerates the verification process on Avail, enabling rollups or standalone chains built on it to take advantage of its fast verification process, providing scalability and flexibility for blockchain designs in the coming years. Compared to Celestia and others, this verification method is a key factor that sets Avail apart.
Celestia uses a secure hash function that is much faster to generate than KZG promises. However, the trade-off with this choice is that they must rely on fraudulent proofs to confirm the accuracy of erasure coding, which can lead to potential delays in ensuring data availability guarantees.
Celestia’s light nodes cannot determine if data is available or wait for pending fraud proof to be received. In other words, due to the challenging period of optimistic verification, the use of fraudulent proofs reduces the ability of light nodes of the network to unambiguously confirm the availability of post-sampled data.
As for EigenDA, it uses KZG promises and downloads only a small amount of data instead of full blocks, and employs proof of validity. Its approach is to split the data into smaller chunks using erasure encoding and requires operators to download and store only a single block, which is a fraction of the size of the full block blob.
As for Ethereum, while the current version does not use proof of validity, EIP-4844 and full Danksharding will be implemented with proof of validity.
Extensibility
The high cost and slow transaction restrictions on Ethereum have contributed to the proliferation of L2s. They have become the executive layer of the future, driving the growth in demand for block space. Currently, the cost of publishing data to Ethereum is estimated to account for 70% to 90% of the total cost of rollups. Expanding the block space will result in additional costs for validators and applications developed on Ethereum.
Base layers such as Avail and Celestia are designed to solve this problem. They are optimized for data availability with the ability to dynamically scale chunk sizes. By incorporating light clients with Data Availability Sampling (DAS), they have the ability to scale the data availability chunk size based on the demands placed on the network. This means that as the block space increases, the applications built on it remain unaffected, as light clients in these networks can execute DAS without having to download the entire block. This unique capability sets them apart from monolithic blockchains.
With a market cap of $191 billion, Ethereum has the largest community. Although protocols built on Ethereum enjoy the benefits of economies of scale, they also face high transaction costs due to the limited block space of the past few years. As Rollup grows and the number of users and transactions peaks, Rollup has become the best choice for execution. As blockchain technology becomes more popular, the demand for block space will only increase.
While DACs can scale with a simplified centralized approach, some Rollups use DACs as a temporary measure until they find a decentralized DA solution.
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Data availability sampling
Both Avail and Celestia support light clients with Data Availability Sampling (DAS), enabling light clients to provide security that minimizes trust. As mentioned earlier, the main differences are how validation is performed and how Avail’s light client P2P network replaces full nodes to support the network in the event of a network outage or bottleneck.
In contrast, Ethereum after EIP-4844 will not be equipped with DAS. This means that its light clients will not have this upgraded, trust-minimized security feature. To complicate matters further, Ethereum’s DA solution is to house its smart contract environment. With full danksharding, DAS will be used to expand blob space, which is expected to be implemented in a few years.
The security of EigenDA is built on trust in a small number of full nodes or other entities because it lacks Data Availability Sampling (DAS). The integrity of the protocol relies on more than half of the committee being honest and at least one additional entity holding copies of the data, similar to optimistic constructs. Although the dual arbitration approach improves security compared to single arbitration, it does not meet the ideal scenario for independent authentication by DAS.
Cost
Ethereum is the most expensive solution in terms of congestion and demand. Even with EIP-4844, Ethereum’s cost is still high because it can only increase block space all at once. DACs are the cheapest, but this comes at the cost of a more centralized approach.
With no execution layer, Avail and Celestia will be able to keep operating costs low. They can also easily grow the block space, which without DAS, current Ethereum cannot do
As for EigenDA, it said it would introduce a flexible cost model for variable and fixed fees, but its actual costs have not yet been announced.
Performance highlights
Now that we’ve reviewed the growth potential, we’ll take a look at the performance of these blockchains.
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Block time
See the table above for information on the time it takes to produce each block.
Measuring the performance of a blockchain by the time it takes to produce a block provides only limited insight because this metric only touches on one aspect of the process from block confirmation to verification completion. Even with a consensus mechanism that provides immediate finality, it may take some time for DA verification using a fraud-proof based method.
Ethereum uses Casper to finalize blocks between 64-95 slots, which means that the final certainty of Ethereum blocks takes about 12-15 minutes.
EigenLayer is not a blockchain, but a set of smart contracts running on Ethereum. This means that it inherits the same final deterministic time as Ethereum. So, if a user sends a transaction to a rollup, the rollup needs to forward the transaction’s data to EigenLayer to prove that the data is available. However, even if RollUp has accepted the transaction, the transaction will only be considered complete after the Ethereum block is finally confirmed, which causes delays. Discussions have taken place on ways to provide faster DA guarantees by adopting cryptoeconomic means.
Block space
As rollups become the future execution layer, the demand for block space will continue to increase. DA layers like Avail and Celestia will be able to adapt to demand because they have a modular design, while the growth of Ethereum’s block space will be limited. Avail’s Kate testnet has configured the block size to 2MB, copied and encoded to 4MB using erasure. Avail is unique in that it can increase the block size using efficient client-side validation techniques. Through internal benchmarks, Avail has tested block sizes up to 128MB without difficulty. As DAS’s demand for block space increases, Celestia is also able to increase the block size.
EigenDA will scale throughput by decoupling DA and consensus, erasure coding, and direct unicast. However, this comes at the cost of the rollups built on it not being able to inherit the censorship resistance of the base layer.
Summary
Choosing a strong base layer to build can be challenging. We hope this article will help readers better understand the pros and cons of different design choices and choose the DA layer that suits them.
