That's one small shard for man, one giant leap for blockchain-kind

Ethereum upgrades have always been a mix of spectacle and subtlety—Dencun's blobs reshaped Layer 2 economics overnight, Pectra's account tweaks whispered promises of smoother user experiences. But the latest fork: Fusaka, activated on December 3, 2025, at epoch 411,392 (around 21:50 UTC), was more of an under-the-hood upgrade that will have broader and longer impacts.

Named after a cosmic nod—"Fulu" for the consensus layer's starry precision, "Osaka" for the Devcon 2025 host city—Fusaka bundles a dozen Eithereum Improvement Proposals (EIPs) into a package. The most noticed is PeerDAS, a data availability sampling mechanism that finally delivers on sharding's 2015 dream without the fanfare of full Danksharding.

At its core, PeerDAS (EIP-7594) lets validator nodes sample tiny chunks of blob data—random slivers, so they don't have to try and process much larger data chunks. Blobs are temporary data sponges for Layer 2 rollups which have been choking bandwidth and spiking fees during peak hours. Now, with erasure coding, nodes can reconstruct the full picture from just over 50% of samples, slashing data loads by up to 85%. This probabilistic verification is robust against 51% attacks because it involves client-side sampling.

As Vitalik Buterin put it on X just after activation:

PeerDAS in Fusaka is significant because it literally is sharding. Ethereum is coming to consensus on blocks without requiring any single node to see more than a tiny fraction of the data.

Fusaka layers in practical polish with EIP-7935 bumping up the block gas limit to 60 million (a 67% jump, gated by caps like EIP-7934 to fend off DoS attacks), while EIP-7825 and others throttle transaction sizes and math operations for greater stability.  Secp256r1 support (EIP-7212) opens the door to phone-native signatures—Face ID for your wallet perhaps?

Blob fee reserve (EIP-7918) aims to smooth volatility, hoarding excess during lulls to flood back in crunches. And the Blob Parameter Only ramps blob capacity 3.5x initially, targeting 14 per block by January, with a soft max of 21—conservative scaling to let the network acclimate.

The ripple effects hit where it counts: Layer 2s. Rollups like Arbitrum and Optimism, already reaching near Visa-levels of throughputs will see a massive fall in fees as settlements zip faster. Congestion eases because validators aren't bandwidth hogs anymore, lowering the bar for solo stakers— a quiet win for more decentralization. L1 Ethereum benefits too, inching toward higher gas limits once ZK-EVMs mature.

Buterin flagged the roadmap ahead in September:

Fusaka will fix this [blob bottlenecks]. But also, safety first... This is all new technology, and the core devs are wise to be super cautious.

It's not flawless. Buterin notes the gaps: L1 scaling lags without ZK-EVMs for O(c²) transaction bursts, proposer bottlenecks persist, and mempools aren't sharded yet. Still, this is a core evolution of one of the most popular blockchains, with sharding not as a monolith, but as probabilistic resilience.

Core dev Marius van der Wijden echoes the measured optimism:

The improvements will take a few months to fully play out, since we will only slowly increase the blobs.

And from ConsenSys' Gabriel Trintinalia:

The Fusaka upgrade really shows that Ethereum is serious about making Mainnet faster.

In a world chasing TPS for usable blockchains, Fusaka might really deliver and help more Ethereum to 100,000 TPS across L2s.