Fusaka Hard Fork Goes Live On Ethereum with Massive Data Availability Boost

Ethereum is set to activate the Fusaka hard fork today, an upgrade designed to improve data availability and scalability across the network. This marks the ecosystem’s second major hard fork of 2025, following the Pectra upgrade that went live earlier this year.

Data and Performance Improvements

The update is scheduled for release at 21:49 UTC, introducing Peer Data Availability Sampling (PeerDAS) and increasing the network’s capacity to support high-throughput Layer 2 rollups.

The feature allows Ethereum validators to verify small, randomly selected portions of data instead of having to download entire blocks. This reduces bandwidth requirements by up to 85%, enabling an up to 8x increase in data throughput for Layer 2 networks that rely on the chain for settlement and security.

To support this, Fusaka has included Blob Parameter Only (BPO) forks, which are small configuration changes that adjust the blob target, blob maximum, and fee update fraction.

The upgrade also increases Ethereum’s block gas limit from 30 million to 150 million units, creating room for more transactions in each block. As a result, Layer 2 networks are expected to see a 40–60% drop in transaction fees, depending on overall chain activity and how quickly different rollups integrate the modifications.

Fusaka further introduces EIP-7825, adding a per-transaction gas cap of about 16.78 million gas. This limit ensures that no single transaction can use an entire block’s capacity, reducing the risk of denial-of-service attacks and laying the groundwork for future execution improvements.

Ethereum Rolls Out Second Major 2025 Hard Fork

The update will be deployed to Ethereum’s mainnet following successful testnet activations on Hoodi, Sepolia, and Holesky. Fusaka is part of the chain’s broader modular roadmap, which aims to separate execution, data availability, and consensus layers to improve scalability without compromising decentralization. It is also the second major hard fork of 2025, following Pectra’s activation, and represents a coordinated improvement to the execution and consensus layers.

Layer 2 networks such as Arbitrum, Optimism, and Base are expected to integrate PeerDAS in the coming weeks. These adoptions will allow them to post more data to Ethereum at lower cost, improving performance for end users and expanding the design space for decentralized applications.

The next scheduled upgrade, Osaka, is expected in 2026 and will introduce blob streaming and stateless validator clients to further reduce costs and improve decentralization.