# Data Availability

In the context of rollups, Data Availability refers to the ability to reconstruct L2 state from the data published on durable storage, commonly stored on L1 (such as Ethereum). Data availability is crucial for asset security, particularly in the event of sequencer failure.

Historically, the cost of data availability has often dominated the gas consumption of rollups. It is encouraging to note that with the activation of EIP-4844 in the Dencun hard fork, this situation has been significantly [improved](https://vitalik.eth.limo/general/2024/03/28/blobs.html). However, uploading data onto blobs may still cost around $0.01 per request, which could become expensive given Vessel's capability to scale up to 1000 TPS.

An alternative to directly committing transaction data onto L1 is to adopt a third-party data availability service or rely on an external Data Availability Committee to store data and provide it on demand. This architecture, known as [Validium](https://ethereum.org/en/developers/docs/scaling/validium/), has become a prevalent choice for deploying rollups and application chains.

Another important consideration for Data Availability is privacy. Trading platforms have different privacy requirements compared to public blockchains, and current Data Availability solutions typically assume that the data provider has access to the entire data history. Vessel Lab is exploring ways to achieve Data Availability while maintaining privacy through Multi-Party Computation (MPC) techniques.
