Solana activates Alpenglow, targeting 150ms transaction finality

Solana has relied on TowerBFT for consensus since its 2020 launch. On Oct. 21, Anza activated Alpenglow on mainnet, replacing TowerBFT and targeting transaction finality in about 150 milliseconds, according to the Solana Foundation’s Alpenglow upgrade page.

For exchanges and merchants, the change is a much shorter wait for a transaction to become irreversible.

How does Alpenglow reach finality faster?

Alpenglow’s Votor protocol changes how validators agree on blocks. Instead of recording validator votes as transactions, validators send votes directly to one another and combine them into certificates; a block becomes final after one or two voting rounds, the Foundation says.

The roughly 150ms figure is a target, down from about 12.8 seconds under TowerBFT. It describes the time to finality, not the interval between blocks. Anza told The Block that the shift condenses Solana’s previous two-step confirmation process into one.

What changes for people using Solana?

Wallet users can keep signing and sending transactions as before: the upgrade changes consensus, not execution, transaction formats or fees, according to the Foundation. Its guidance says most application developers who only send transactions and read account state have nothing to migrate.

For exchanges crediting deposits and merchants processing payments, faster finality can shorten the wait before treating a transfer as settled. The upgrade also removes validator vote transactions from blocks, so transaction counts may fall even if user activity does not. Apps and dashboards that counted those votes will need to account for the change.

What must validators do to stay online?

Operators need to run an Agave-based client, such as Agave, Jito-Solana or Harmonic Salsa version 4.3.2, and keep at least 0.8 SOL above the rent-exempt minimum in the vote account, the Foundation says. That balance pays a Validator Admission Ticket fee each epoch; if the account cannot pay, the validator will not vote or produce blocks in the following epoch.

Firedancer and Frankendancer were not supported for the migration, so operators using either had to switch clients for it. The Foundation says Alpenglow is rolling out in two phases: Votor is live, while Rotor, which is intended to change how block data travels across the network, is planned for a later release with no schedule yet.

Sources

• the Solana Foundation’s Alpenglow upgrade page — solana.com
• The Block — theblock.co