Ethereum's Fusaka upgrade is now live on mainnet, bringing major structural changes to the way the network handles data and scaling. The upgrade went live at epoch 411392 21:49:11 UTC, with the official Ethereum account first activating “Upgrade in progress… Fusaka @ epoch 411392 // 21:49:11 UTC” and then signaling “Fusaka is live on the Ethereum mainnet!”
In its announcement, the account highlighted three key elements of Fusaka: PeerDAS now “unlocks 8x data throughput for rollups,” significantly expanding the amount of data that rollup-based layer 2 networks can publish to the network. The upgrade also introduces “UX improvements with R1 curves and pre-checks,” and is stated to be “prepared for L1 expansion with increased gas limits and more.” The project added that community members and core developers will “continue to monitor the issue over the next 24 hours.”
Why Husaka is ‘important’ to Ethereum
Vitalik Buterin explained the essence of the upgrade in very direct terms. “Fusaka’s PeerDAS is important because it is literally sharding,” he wrote. “Ethereum is reaching consensus on blocks without a single node needing to see more than a small portion of the data. And it is robust against 51% attacks. It is client-side probabilistic verification, not validator voting.” This means that the network can now rely on client-side probabilistic verification to agree on blocks, even if no node has to download all the relevant data.
Buterin connects this to a long-term line of research, noting that “sharding has been a dream for Ethereum since 2015, and data availability sampling since 2017,” and links back to earlier research work on data availability and erasure coding. With Fusaka, that architecture is no longer just a roadmap concept, but a live mechanism that secures Ethereum's data layer.
At the same time, Buterin made it clear that Fusaka has not completed its sharding roadmap. He emphasized, “There are three reasons why Husaka’s sharding is incomplete.” First, he argues that “we can handle O(c^2) transactions (where c is per-node compute) in L2, but not in Ethereum L1,” adding, “We need a mature ZK-EVM to scale to also benefit Ethereum L1 beyond what can be achieved through constant element upgrades like BAL and ePBS.”
Second, he pointed out the “proposer/builder bottleneck” where “builders have to have the entire data and build the entire block,” and said, “It would be amazing if decentralized block construction was possible.” Third, he was blunt: “We don’t have a sharded mempool. We still need it.”
Despite these caveats, Buterin called Fusaka “a fundamental step forward in blockchain design.” “Over the next two years, there will be time to improve the PeerDAS mechanism, carefully scale it up while continuing to ensure stability, use it to scale L2, and once ZK-EVM matures, transition in-house to also scale Ethereum L1 gas,” he argued.
“A huge congratulations to the Ethereum researchers and core developers who have worked hard for many years to make this happen,” he said, concluding by emphasizing that for the Ethereum community, Fusaka is not a routine protocol update, but the arrival of the long-promised era of sharding on the mainnet.
At press time, ETH was trading at $3,194.
Featured image created with DALL.E, chart from TradingView.com
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