Setting Up Blob Storage for Availability Data

Blob storage is a foundational component for modern blockchain scalability, specifically for data availability (DA). Unlike storing data directly in a block's execution payload, blobs are large, temporary data packets attached to blocks. This separation, pioneered by EIP-4844 (Proto-Danksharding) on Ethereum, allows Layer 2 rollups to post transaction data cheaply without congesting the main execution layer. The core guarantee is that this data is available for download and verification by any network participant for a short window, typically 1-2 weeks, which is sufficient for fraud or validity proofs.

To set up blob storage, you first need a client that supports the blob-carrying transaction type. For Ethereum, this means using a consensus client (e.g., Prysm, Lighthouse) and an execution client (e.g., Geth, Nethermind) that have implemented EIP-4844. The key new transaction type is BLOB_TX_TYPE (type 0x03). When constructing this transaction, you specify one or more blobs in the blob_versioned_hashes field. Each blob is exactly 4096 field elements (131,072 bytes), and clients use a KZG commitment (a cryptographic proof) to commit to the blob's contents efficiently.

Here is a simplified conceptual flow for a rollup operator posting data:

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# 1. Batch L2 transactions into a blob
transaction_batch = serialize_l2_transactions(batch)
blob_data = encode_to_blob_format(transaction_batch)

# 2. Generate a KZG commitment and proof
kzg_commitment, kzg_proof = kzg.commit(blob_data)

# 3. Construct and send the blob transaction
tx = BlobTransaction(
    to=ROLLUP_CONTRACT_ADDRESS,
    blob_versioned_hashes=[blob_hash_from_commitment(kzg_commitment)],
    max_fee_per_blob_gas=...,
    blobs=[blob_data]
)
send_transaction(tx)

The blob data is propagated across the blob sidecar network, a dedicated peer-to-peer subnetwork, ensuring nodes can retrieve it.

For data availability sampling and long-term storage, you need to interact with blob retrieval networks. After a blob transaction is included in a block, nodes store the blob data in a temporary cache. Services like EigenDA, Celestia, or Avail provide specialized DA layers with different trade-offs in cost, throughput, and guarantees. To retrieve a blob for verification, you query these networks using the blob index and block hash. The Ethereum Beacon Chain API provides an endpoint (/eth/v1/beacon/blob_sidecars/{block_id}) to fetch sidecars, which contain the blobs and their proofs.

Critical best practices include monitoring blob gas prices, which fluctuate separately from regular gas, and implementing pruning logic. Since nodes only guarantee blob availability for ~18 days (4096 Epochs on Ethereum), applications must ensure critical data is migrated to permanent storage (like IPFS, Arweave, or a contract's calldata) before this window closes. Failure to do so renders the data unavailable, breaking the security model for rollups. Tools like the Ethereum Beacon Chain explorer can be used to verify blob inclusion and availability status.

Implementing robust blob storage is essential for any L2 or high-throughput dApp. The setup reduces data posting costs by over 10x compared to calldata, directly enabling cheaper transactions. By understanding the client configuration, transaction lifecycle, and retrieval mechanisms, developers can build scalable applications that leverage this new primitive while maintaining the decentralized security guarantees of underlying blockchains.

Data availability (DA) ensures that all transaction data for a new block is published and accessible, allowing nodes to independently verify state transitions. For Layer 2 rollups, this data is typically posted as blobs to a Layer 1 like Ethereum or a specialized DA layer. Setting up robust blob storage is a prerequisite for running a sequencer, a validator, or an indexer that needs to fetch and verify this data. You will need a basic understanding of Ethereum's EIP-4844 (Proto-Danksharding) or the equivalent data structure on other DA layers.

The core technical requirement is access to a blob storage endpoint. For Ethereum, this is an execution client (e.g., Geth, Nethermind, Besu) with the --blobpool.datadir flag configured and the eth_getBlobSidecars JSON-RPC method enabled. For Celestia, you interact with the Blob module via gRPC or REST. For Avail, you use the Kate RPC. Ensure your node is synced to the network you intend to use. You can also use a trusted RPC provider that supports blob queries, but running your own node offers the highest data integrity and availability guarantees.

Your development environment should include a language SDK for interacting with the storage. For Ethereum blobs, you will need the Ethereum Execution API specification and a library like ethers.js (v6+) or web3.py. For other DA layers, install their official SDKs (e.g., @celestiaorg/js-sdk, avail-js-sdk). You will use these to construct, submit, and retrieve blobs. Basic command-line proficiency is necessary for node management and running scripts. We will assume the use of Node.js and npm/yarn for JavaScript examples, but the concepts apply to other stacks.

Before writing code, test connectivity to your blob source. For an Ethereum node, call eth_getBlobSidecarsByRange to fetch recent blobs and verify the response. For a Celestia light node, query the Blob.GetAll endpoint. This confirms your setup can access the data pipeline. You should also understand the blob lifecycle: blobs have a short persistence window on-chain (e.g., 18 days on Ethereum post-EIP-4844) before being pruned. Your application needs a strategy for long-term archival, which may involve subscribing to blob events and saving them to a database or decentralized storage like IPFS or Arweave.

Finally, set up a project structure. Initialize a new directory with your package manager, install the required SDKs, and create configuration files for network RPC URLs and chain IDs. We will build a simple script that listens for new blobs, decodes them using the appropriate SSZ or Protobuf schema, and verifies their inclusion via a KZG commitment or Merkle proof. This foundational setup is applicable for building data availability sampling clients, bridge attestation systems, or rollup fraud proof verifiers.

Data availability (DA) layers ensure that transaction data is published and accessible for verification, a critical component for scaling solutions like rollups. Blob storage is a cost-effective method for posting this data, introduced on Ethereum via EIP-4844 (proto-danksharding). Instead of storing data permanently in calldata, blobs are large data packets (~128 KB each) attached to blocks and available for a short window (~18 days). This guide walks through the core concepts and setup for interacting with blob storage.

To work with blobs, you need to understand the key components. The blob transaction is a new Ethereum transaction type containing one or more blobs. Each blob is a 4096-field element vector of 32 bytes each, totaling 131,072 bytes. Clients and nodes use a sidecar mechanism to distribute blob data separately from block bodies. For development, you can use a local testnet like Devnet 11 which supports the Cancun upgrade, or connect to the Holesky testnet for a more production-like environment.

Interacting with blob storage requires updated tooling. Use an EIP-4844 compatible client such as Geth (v1.13+) or a dedicated library like EthereumJS. The following code snippet shows how to construct a simple blob transaction using the ethers.js v6 library, which has added experimental support for blobs.

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import { ethers } from 'ethers';
// Create a blob from your data
const data = "0x" + "your_availability_data_here".padEnd(131072*2, '0'); // Hex string
const blob = ethers.Blob.from(data);
// Build the transaction
const tx = {
    to: '0xRecipientAddress',
    value: ethers.parseEther('0.001'),
    blobs: [blob],
    maxFeePerBlobGas: ethers.parseUnits('10', 'gwei'), // Blob gas price
};
// Send the transaction (requires a signer and 4844-ready provider)
const sentTx = await signer.sendTransaction(tx);

After submitting a blob transaction, you must verify its availability. Nodes expose a new JSON-RPC method, eth_getBlobSidecar, to fetch the sidecar data for a given block. Rollup sequencers or anyone needing to verify data should call this method and perform a KZG commitment proof to ensure the retrieved data matches the commitment posted on-chain. The Ethereum Beacon Chain API also provides endpoints for querying blob data. It's crucial to download and verify blobs within their availability window before they are pruned by nodes.

For production systems, consider using a blob storage provider like EigenDA, Celestia, or Avail for dedicated, high-throughput data availability. These layers often provide their own SDKs and more generous data persistence. The setup involves deploying your rollup contracts to your target chain (e.g., Ethereum Mainnet) and configuring your node software to post data to your chosen DA layer via its specific APIs and transaction formats, which may differ from Ethereum's native blobs.

Best practices for blob storage include monitoring blob gas prices, which fluctuate independently from execution gas, and implementing data redundancy by posting to multiple DA layers for critical applications. Always test your integration thoroughly on testnets, and consult the latest documentation for Ethereum Execution APIs and your chosen DA provider to handle updates like full danksharding, which will increase blob capacity per block.

EIP-4844 introduces blob-carrying transactions as a new transaction type. Unlike calldata, blob data is not accessible to the EVM but is committed to by the consensus layer, providing a large, temporary data space for Layer 2 rollups. The primary goal is to significantly reduce the cost of data availability for rollups. Each blob is approximately 128 KB, and transactions can carry up to 6 blobs. This data is stored by beacon chain validators for a short period (currently ~18 days) before being pruned, ensuring it is available for nodes to sync and verify.

To implement blob handling, you must interact with the new BlobTransactionNetworkWrapper and ExecutionPayload structures. Your client or node software needs to support the BlobSidecar subnet on the P2P network (topic: /eth2/beacon_block/ssz_snappy). When you receive a beacon block with blobs, you must validate the KZG commitments and proofs against the blob data. The key libraries for this are the KZG cryptography libraries (e.g., c-kzg-4844) and the consensus specifications defined in the Ethereum Consensus Specs.

For a practical setup, start by configuring your execution client (e.g., Geth, Nethermind) and consensus client (e.g., Lighthouse, Prysm) with EIP-4844 support enabled. You will need to handle the BlobSidecar messages. Here is a conceptual outline in pseudocode for processing incoming blobs:

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# Pseudocode for blob validation
sidecar = receive_blob_sidecar(p2p_network)
blob = sidecar.blob
kzg_commitment = sidecar.kzg_commitment
kzg_proof = sidecar.kzg_proof

# Verify the KZG proof
assert kzg_verify(blob, kzg_commitment, kzg_proof)

# Store the blob indexed by its commitment
blob_storage[commitment] = blob

Storage can be a simple in-memory cache or a database, but it must be garbage-collected after the retention period.

The most critical operational aspect is ensuring data availability. Your node must serve blob data upon request from other peers during the retention window. Failure to do so can lead to missed attestations or being penalized by the network. Monitor your blob cache size and P2P request success rates. Tools like the Ethereum JSON-RPC API have been extended with methods like eth_getBlobSidecars for fetching blob data. Always reference the latest specifications, as parameters like the MAX_BLOBS_PER_BLOCK (currently 6) and BLOB_TX_TYPE (0x03) are subject to change with network upgrades.

Celestia's modular Data Availability (DA) layer provides a secure and scalable solution for publishing large data blobs, such as rollup transaction data, off-chain. Unlike monolithic blockchains that process and store all data on-chain, Celestia specializes in guaranteeing that data is available for download by any network participant. This is achieved through a technique called Data Availability Sampling (DAS), where light nodes can cryptographically verify data availability without downloading entire blocks. For developers, this means you can post your application's data—like L2 batch transactions or state diffs—to Celestia as a blob and rely on its network for robust availability guarantees.

To interact with Celestia, you primarily use its Blobstream and gRPC interfaces. The process begins by formatting your data into a Blob, which is a namespaced data structure. Each blob is associated with a namespace ID, allowing for data segregation and efficient retrieval. You submit blobs via a Celestia light node using the SubmitPayForBlob transaction, which pays for the blob's storage in TIA, Celestia's native token. The critical output of a successful submission is a commitment, such as a Merkle root, and proof of inclusion, which your rollup or chain can store as a compact verification handle on its own ledger.

Here is a conceptual outline of the submission flow using a light node client:

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# Pseudocode for blob submission
from celestia_light_client import CelestiaClient

# 1. Connect to a Celestia light node
client = CelestiaClient("grpc.celestia.org:9090")

# 2. Prepare your data and namespace
namespace = "0x00010203040506070809"
blob_data = serialize_transaction_batch(batch)

# 3. Submit the PayForBlob transaction
tx_response = client.submit_pay_for_blob(
    namespace_id=namespace,
    data=blob_data,
    fee=1000 # utia
)

# 4. Extract proof for your L1 contract
commitment = tx_response.commitment
proof = tx_response.proof

After submission, the data is ordered in Celestia blocks and becomes available for sampling.

Retrieving the data is equally important. Applications like fraud prover or ZK validity circuits need to fetch the blob data to verify transactions or compute state transitions. You can query for blobs by their namespace ID and height (block number) using the GetAll gRPC endpoint. The returned data includes the original blob and inclusion proofs, allowing the verifier to confirm the data is part of the canonical Celestia chain. This decoupled architecture means your execution layer only needs to store tiny commitments on-chain while the bulky data is efficiently handled by Celestia's dedicated DA network.

When integrating, consider key parameters like blob size limits (currently 2MB per blob on mainnet), namespace design for your application, and gas costs for submission. For production systems, monitor Celestia's data availability sampling security assumptions and the operational status of the Blobstream oracle contract on your settlement layer (like Ethereum). Proper integration reduces your L1 gas fees by over 90% for data posting, shifting the cost and scalability bottleneck to an optimized DA layer. Start testing on Celestia's Mocha testnet using the official documentation and Node APIs before deploying to mainnet.

EigenDA is a data availability (DA) service built on top of EigenLayer, which allows Ethereum stakers to restake their ETH to secure additional protocols. Unlike traditional DA solutions that require separate token staking, EigenDA leverages the existing economic security of Ethereum through restaked ETH. This provides rollups and Layer 2s with high-throughput, low-cost blob storage, backed by a cryptoeconomic security model that is an extension of Ethereum's own. The core component is the blob, a large data packet introduced by Ethereum's EIP-4844, which EigenDA operators commit to and make available.

To use EigenDA, a rollup's sequencer must be configured to post its transaction data (the rollup's state diffs or transaction batches) as blobs to the EigenDA network instead of directly to Ethereum calldata. The process begins by integrating the EigenDA client libraries into your rollup node. You will need to interact with the EigenDA smart contracts on Ethereum to register your rollup, pay fees in ETH, and submit data attestations. The primary steps are: - Registration: Deploy a service manager contract and register your rollup chain with EigenDA. - Blob Dispersion: Encode your batch data into a blob and disperse it to a committee of EigenDA operators. - Attestation: Collect signatures from operators proving they have stored the data. - Verification: Post the attestation to the EigenDA contract on Ethereum to finalize availability.

A basic code snippet for dispersing a blob using the EigenDA Typescript SDK illustrates the client-side process. First, you must initialize a disperser client connected to the EigenDA network.

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import { disperser } from '@eigenlayer/da-client';

const client = new disperser.Disperser('https://disperser.eigenda.xyz');
const blobData = // Your encoded batch data as a Uint8Array
const securityParams = { quorumId: 0, adversaryThreshold: 25, quorumThreshold: 50 };

const blobHeader = await client.disperseBlob(blobData, securityParams);
const confirmation = await client.getBlobStatus(blobHeader);

This sends the blob to the operator network and retrieves a confirmation receipt containing the attestation signatures required for on-chain verification.

The security and cost model is defined by quorums. A quorum is a subset of EigenDA operators with specific staking requirements. When dispersing a blob, you specify a quorum ID (e.g., 0 for the primary ETH restaked quorum). The parameters adversaryThreshold and quorumThreshold define the security level, representing the percentage of operators that must be honest and the percentage that must attest, respectively. Fees are paid in ETH and are dynamically priced based on blob size and the selected quorum's capacity. This is typically orders of magnitude cheaper than posting equivalent data to Ethereum L1 calldata.

After dispersing a blob and receiving attestations, the final step is on-chain verification. The rollup's contract (or a dedicated verifier) must call the EigenDA contract's confirmDataAvailability function, submitting the blob header and the aggregated operator signatures. This function verifies that a sufficient quorum of restaked operators has attested to storing the data. Once confirmed, the data is considered available, and the rollup's state transition can be safely executed. This on-chain proof is what allows fraud proof or validity proof systems to challenge or verify the rollup's transactions.

For production deployment, consider monitoring operator performance, setting up redundant dispersal to multiple quorums for higher security, and implementing a fee estimation strategy. The EigenDA ecosystem includes tools like the EigenDA Explorer to track blob status and operator sets. By leveraging restaking, EigenDA provides a scalable DA layer that aligns its security directly with Ethereum, offering a compelling alternative for rollups seeking to reduce costs while maintaining strong cryptographic guarantees for data availability.

This guide walked through the essential steps for setting up blob storage using Filecoin's FVM and IPFS/Filecoin Saturn for retrieval. You now have a functional pipeline: a smart contract on the Filecoin Calibration testnet that stores Content Identifiers (CIDs) on-chain, paired with a Node.js script that pins data to an IPFS node via Lighthouse.storage and fetches it through the Saturn CDN. This architecture separates the consensus-critical proof of storage on-chain from the high-performance data delivery layer.

The key concepts implemented are content addressing via CIDs, which guarantees data integrity, and decentralized storage incentives through Filecoin's storage provider market. For production systems, consider these next steps: migrate to Filecoin mainnet for cryptoeconomic security, implement redundancy by storing identical blobs with multiple storage providers, and set up monitoring for your CIDs using services like Textile's Buckets or FVM's built-in state queries to ensure data remains available and retrievable.

To deepen your understanding, explore related protocols. EigenDA and Celestia offer alternative data availability architectures that use similar principles of data availability sampling (DAS). The Ethereum EIP-4844 (proto-danksharding) standard introduces a native blob-carrying transaction type, creating a direct bridge between execution and data availability layers. Experimenting with these will clarify the trade-offs between on-chain data availability, external DA layers, and modular blockchain design.

For further development, consult the official documentation for the Filecoin Virtual Machine, the Lighthouse.storage SDK, and the Saturn Network. The code examples provided are a foundation; you can extend them to handle batch uploads, automated renewal of storage deals, or integration with an L2 sequencer to automatically post transaction data blobs.