Solana activates Alpenglow, targeting 150ms finality

Solana activated Alpenglow on Oct. 21, replacing its TowerBFT consensus system with a protocol targeting transaction finality in about 150 milliseconds, according to The Block’s report on the mainnet launch. Anza, Solana’s core engineering firm, said the upgrade reached mainnet at slot 459,653,000, about 14:00 UTC.

The change replaces a consensus system Solana had used since its March 2020 launch. The 150-millisecond figure is a target; Anza’s statement, reported by The Block, compares it with about 12.8 seconds under TowerBFT.

How does Alpenglow change transaction finality?

Alpenglow moves validator votes off-chain and bundles them into certificates, according to the Solana Foundation’s upgrade overview. Under TowerBFT, validators sent votes as transactions, and blocks became final after enough votes accumulated over 32 slots; Alpenglow can finalize a block in one or two rounds of voting.

The shift changes how validators agree on blocks, while transaction execution, programs and fee mechanics remain the same, the Foundation says. Users do not need to change how they sign or send transactions.

What happened at the mainnet handoff?

The Foundation says epoch 1064 began at about 13:36 UTC on Oct. 21, with TowerBFT continuing for 5,000 slots before Alpenglow took over. The genesis block was slot 459,652,999; votes from 446 of 654 validators certified it.

Solana’s vote transactions are no longer included in blocks, according to the Foundation. That changes transaction counts that included validator votes, even though the protocol’s execution and user transactions continue.

What remains to come?

Alpenglow’s planned second phase, Rotor, would replace Turbine, Solana’s block-data distribution protocol, with a relay layer. The Foundation says Rotor is planned for a later release but has no schedule; it has not confirmed a mainnet date.

Source material

• The Block’s report on the mainnet launch — theblock.co
• Solana Foundation’s upgrade overview — solana.com