Solana activates Alpenglow, targeting 150ms finality

Solana activated Alpenglow on its main network on Wednesday, replacing the consensus system it has used since 2020 and aiming to make transactions final in about 150 milliseconds. That could let services such as exchanges and merchants treat payments as settled sooner. The Solana Foundation’s Alpenglow update says the protocol switched on during epoch 1064, which began at about 13:36 UTC on October 21.

Consensus is the process validators use to agree on which transactions happened and when they can no longer be reversed. Under the old TowerBFT system, finality took about 12.8 seconds, according to Solana. The new target is roughly 150 milliseconds, but the Foundation describes that as a target, not a guarantee for every transaction.

How does Alpenglow change Solana’s transaction process?

Alpenglow’s first phase, called Votor, changes how validators confirm blocks. Under TowerBFT, validators sent votes as transactions, and a block became final after enough votes accumulated over 32 slots. With Votor, validators send votes directly to one another and combine them into certificates, records showing that enough validators agreed. A block can then become final after one or two rounds of voting, the Foundation says.

The change affects agreement on blocks, while transaction execution stays the same. Solana says the upgrade leaves its transaction formats, fees, programs and Solana Virtual Machine—the software that runs programs on the network—untouched. Wallets and apps can keep working as before.

What changed when Alpenglow took over?

Solana’s account says the network ran TowerBFT for the first 5,000 slots of epoch 1064 before handing off to Alpenglow at slot 459,653,000. The final TowerBFT block, at slot 459,652,999, became the starting point for the new system. The handoff took about 900 milliseconds, according to the Foundation.

For users, the main expected change is faster finality. The upgrade also changes what infrastructure developers need to track: validator vote transactions no longer appear in blocks, and some block data streams now need to handle more than one candidate block per slot. That may change transaction counts shown on dashboards even if user activity does not fall.

The launch covers Votor, the voting protocol. A second planned phase, Rotor, would change how block data spreads across the network, but Solana says it is not yet scheduled. The Block reported Anza’s mainnet announcement and said further protocol changes have no confirmed release dates.

Sources

• Solana Foundation’s Alpenglow update — solana.com
• reported Anza’s mainnet announcement — theblock.co