In blockchain networks, Data Availability is vital to ensure every network member can access and verify information stored on the blockchain, including transaction details, block data and status ledger.
What is data availability?
Data availability (DA) refers to the availability of data to validate whether transactions within the block are valid or not to network participants.
Simply put, data availability is like live streaming a sports match. DA allows anyone to download transactions to see what happened, just like live streaming allows anyone to watch the match if they are not at the stadium.
The concept of Data Availability gained more attention when the term Modular Blockchain appeared. The DA layer is located between Settlement and Consensus to screen and ensure the data has no corruption before receiving consensus from validators and completely freezing it at the Consensus layer.
No matter how powerful the Execution layer is, network throughput is limited by data availability.
Distinguish between Data storage and Data availability
These two concepts, although both related to data, have completely different roles. First of all, Data Storage, or "Data Storage", plays the role of storing data in a decentralized space. It ensures that historical data can be retrieved quickly in the event of loss or failure.
In contrast, Data Availability (DA) lies at the stage before new data is created. Data Availability is a step that helps Validators/Nodes in the network ensure that they have enough reliable data from the past to validate and create new data. After new data is created, it returns to the storage phase of Data Storage, and this process will continue to repeat in the future.
Data Availability Solution:
Let's look at two distinct types of DA layers:
Data Availability Sampling (Data Availability Sampling):
This is the technique that blockchain uses to ensure that all light nodes can access the necessary blockchain data without the need to download and verify the entire data set.
The process starts by dividing the blockchain data into smaller pieces. Nodes can randomly select some of these parts instead of the entire dataset. This reduces the burden on individual nodes, as they only need to process a small portion of the total amount of data.
Data Availability Committee:
The Data Availability Committee (DAC) is a group of trusted nodes in the blockchain network, tasked with ensuring data availability. The main role of the DAC is to verify that all data, such as transactions and state changes, are stored correctly and accessible by any network member. DAC members are typically selected through the DAO to minimize single points of failure and other centralization risks.
DACs play an important role in Layer 2 scaling solutions, such as Rollups, where they can help manage data related to off-chain computation. In sharded blockchains, where data sets are distributed across different shards, DAC helps ensure data availability across all shards.
Why is Data availability important?
Web apps need to store huge amounts of data, so cloud computing companies have to build huge data centers to handle that volume of data. Similarly, DA also creates a "bottleneck" for Dapps on every blockchain.
Especially for rollups and layer 2 blockchains, DA is a significant limitation. Low DA traffic leads to high transaction fees, limiting the type of applications developers can build.
In general, DA costs account for about 95% of the total cost of the rollup. Once DA is no longer a bottleneck, developers can unlock new monetization opportunities and the ability to build fully on-chain applications.
However, DA is not just a resource that Rollups consume. DA allows anyone to directly verify whether the blockchain chain is working correctly. Until now, Rollups had to rely on small Committees to resolve DA bottlenecks. That means anyone wanting to interact with Rollups must rely on trusted third parties to access and verify the network. Therefore, overcoming the DA bottleneck by using proofs instead of Committees allows rollups to regain verification capabilities.
Current challenges of Data Availability:
Cross-chain interoperability: As blockchain technology continues to develop, different networks are introducing their own approaches to data availability. While this can spur innovation, it can also create challenges related to cross-chain operations, i.e. how different blockchain systems interact with each other.
The balance between scalability and security: Improving data availability can enhance scalability, but can also lead to reduced security. It is important to consider the potential impacts of data availability solutions before implementing them. The classic balance between security and scalability is also described in the “Blockchain trilemma“.
Conclude
In blockchain networks, data availability refers to the ability of network members to access and verify data stored on the blockchain. There are many different data availability solutions, including data availability layers, data availability sampling, and data availability committees. Going forward, data availability will likely continue to play an important role in the widespread adoption of blockchain technology.
