Although primarily intended to expand data capacity for Layer-2 networks, the Fusaka upgrade introduces a suite of protocol changes that collectively aim to boost Ethereum throughput and lower costs, while requiring coordinated validator upgrades and careful monitoring to avoid network disruption. The upgrade, scheduled for mainnet activation around December 3, 2025, follows successful testnets including Hoodi, Holesky, and Sepolia, and builds directly on the 2024 Dencun improvements by further expanding blob usage for Layer-2 data storage. Validators and node operators must upgrade in a coordinated manner to the specified block height activation, because desynchronized clients could create temporary validation gaps, and monitoring is advised during the phased rollout to detect issues early. The staged deployment includes the initial fork, a December 17 blob capacity increase, and a January 7 follow-up hard fork, allowing network participants to observe effects and adjust operations. A final testnet named Hoodi went live recently to validate the upgrade’s behavior under realistic conditions and developer load, confirming readiness for mainnet, and this testing was part of the careful pre-launch process led by core teams; the testnet results emphasized robust stability. The rollout also follows a planned schedule that aims to more than double data handling capacity across Layer-2s through phased blob increases and protocol tweaks, reflecting the broader goal of scaling Ethereum via gradual capacity expansion.
Fusaka expands blob capacity for Layer‑2s, boosting throughput and cutting costs while requiring coordinated validator upgrades and careful rollout monitoring
A central technical component of Fusaka is Peer Data Availability Sampling, or PeerDAS, which permits validators to verify small fragments of blob data rather than downloading full blobs, and this change substantially reduces node resource requirements while preserving data availability guarantees. PeerDAS increases effective blob space by over 400 percent, a change that is expected to elevate Layer-2 throughput substantially, and Ethereum leadership has characterized the mechanism as key to Layer-2 scaling. By lowering storage and bandwidth demands on validators, PeerDAS aims to decrease operational costs and make Layer-2 transaction validation faster and cheaper, approaching near-zero incremental costs for some operations.
The upgrade also raises the block gas limit and introduces parallel smart contract execution through EIPs such as 7825 and 7935, measures intended to increase on-chain transaction processing capacity, and projections indicate potential throughput improvements toward 12,000 transactions per second from current estimates near 3,100 TPS. Gas fees are expected to fall as expanded blob use and efficient sampling shift Layer-2 data handling off-chain temporarily and reduce on-chain congestion, and EIP-7594 complements these changes.
Risks remain, including the complexity of coordinated upgrades and potential unforeseen interactions in staged forks, so operators and developers are advised to follow release notes closely and participate in monitoring to maintain network stability.
