Quick breakdown
- Fusaka upgrade launches December 3, 2025, introducing PeerDAS to enhance Ethereum scalability.
- PeerDAS allows nodes to verify data availability by sampling chunks instead of full downloads.
- Blob capacity will double, with gradual increases planned in early 2026 for cheaper rollups.
Ethereum targets scalability with Fusaka upgrade
Ethereum co-founder Vitalik Buterin has confirmed that the network’s upcoming Fusaka upgrade, scheduled for December 3, will address critical data availability challenges. At the core of the upgrade is PeerDAS (Peer Data Availability Sampling), a system designed to allow nodes to verify blockchain data without downloading it in full.
“PeerDAS is trying to do something pretty unprecedented: have a live blockchain that does not require any single node to download the full data,”
Buterin said on Thursday, stressing its importance for scaling both Ethereum layer 2s and eventually layer 1 itself.
How PeerDAS improves scalability
Instead of forcing nodes to store entire blockchain data, PeerDAS lets them download smaller “chunks” and statistically sample them to confirm data integrity across the network. This method was first introduced in Ethereum Improvement Proposal (EIP) 7594 in January 2024.
The system plays a crucial role for rollups, Ethereum’s layer-2 scaling solutions, which currently face bottlenecks tied to limited layer-1 data availability. As EIP-7594 outlines, enhancing data availability directly improves rollup throughput and reduces costs for end users.
Blob usage hits record levels ahead of upgrade
Buterin’s remarks came after Dragonfly’s head of data, Hildebert Moulié, noted that Ethereum had reached its six blobs per block target for the first time this week.
1/ we hit 6 blobs/block for the first time
quick update below on current blob usage pic.twitter.com/ZnBWRSPZVj
— hildobby (@hildobby) September 24, 2025
Blobs, introduced in the Dencun upgrade via EIP-4844 (proto-danksharding) in March 2024, are a specialized form of storage aimed at lowering transaction costs for rollups. The Fusaka upgrade will double blob capacity from the current 6/9 target/maximum per block.
Buterin cautioned that developers remain “super cautious on testing” given the novelty of the technology, with blob counts set to rise conservatively before scaling more aggressively.
Gradual blob expansion through 2025
Following Fusaka’s launch, two Blob Parameter Only (BPO) forks are planned. The first, later in December, will raise the maximum blob count from 9 to 15, while the second in January 2025 will push it further to 21, according to Ethereum researcher Christine Kim.
Developers expect this phased rollout to vastly improve Ethereum’s scalability while keeping network stability intact.
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