Alternative Data Availability (DA) for AppRollups

Alternative Data Availability (DA) for AppRollups

We're proud to announce that Caldera chains can now opt in to use alternative data availability (DA) solutions in place of standard Ethereum DA!

Why do we need DA?

Well, in order to make sure that any invalid transactions can be caught and reverted on a rollup, users need a way to make sure that the rollup's block data is actually published.

How is that solved for at the moment? Right now, the vast majority of Ethereum rollups solve this by simply posting all of the rollup blocks onto Ethereum and relying on it for data availability.

But, there's a downside: Ethereum DA is expensive!

This standard approach can lead to extremely high and volatile costs, as rollups are forced to compete for limited blockspace with all other dApps and users transacting on Ethereum.

As a result, over 95% of the cost of a rollup transaction today comes from posting data to Ethereum. For reference, both Arbitrum and Optimism have spent over $10m on data availability costs on Ethereum this year!

So, how do we improve upon Ethereum DA? Well, it's worth noting that rollups inherently only use traditional blockchains (eg. Ethereum) as a DA layer to dump transactions, but all of the actual transaction processing and computation happens on the rollup itself.

This highlights an exciting realization: a blockchain doesn’t actually need to handle any computation on its own, it only needs to order transactions into blocks, and guarantee the data availability of transactions.

Enter stage: Alternative DA.

Introducing Alternative DA

Alternative DA systems take advantage of this insight to separate out DA from settlement through various innovative approaches, dramatically lowering data costs and increasing throughput to significantly improve rollups' long-term scalability.

At the moment, we're proud to offer Celestia as our first Alt-DA solution for all Caldera chains, leveraging their Data Availability Sampling (DAS) and Namespaced Merkle Trees (NMTs) to save significant costs for the chains in our ecosystem.

Our Celestia Integration

While a normal OP stack rollup might create up to $50k/month in DA costs, our Alt-DA OP stack integration is able to save around 75% of the total costs for running that rollup! We accomplish this by modifying the OP-batcher such that the first byte (either 0 or 1) of batch data submitted indicates where rollup data has been posted:

  • 0 for Ethereum
  • 1 for Celestia

From there, type 0 submits batches as normal Ethereum calldata, while type 1 submits data to Celestia and posts a pointer on chain, which includes the block height and transaction commitment.

The OP-node then checks the blob data on Celestia against the commitment posted on-chain and drops the batch if the commitment doesn't match.

To preserve uptime and security, our implementation allows an OP stack integration to fall back to Ethereum DA in case data can't be submitted to Celestia (which might happen if Celestia becomes more expensive or congested).

In addition to this OP Stack implementation, we're excited to support Alt-DA Arbitrum Orbit with Celestia as well, in light of their recent integration!

Get Started Now

Testnets for both Manta Pacific and Celestia Bubs already use this Alt-DA OP Stack implementation, which is extendible and can support arbitrary DA layers!

We're incredibly proud to be on the front lines of the modular future, and plan to offer more leading Alt-DA solutions to our customers in the coming months.

If you're interested in launching a production-grade rollup with Alt-DA, don't hesitate to contact us!