Solana activates Alpenglow, targeting 150ms finality

Solana’s validators have used the TowerBFT consensus system since the network launched in 2020; on Oct. 21, the network activated Alpenglow, a replacement that changes how blocks reach finality. The Solana Foundation’s Alpenglow update says the upgrade went live at the start of epoch 1064, at about 13:36 UTC.

For users, the change is designed to make payments and trades settle sooner without requiring a new wallet or changing transaction fees.

How does Alpenglow change finality?

Alpenglow replaces TowerBFT’s on-chain voting with direct validator-to-validator votes, which are combined into certificates. The Foundation says blocks can then become final after one or two voting rounds, compared with votes accumulating over 32 slots under the previous system.

The target is about 150 milliseconds for finality, down from roughly 12.8 seconds under TowerBFT, according to the Foundation. Finality is the point at which an application can treat a transaction as settled and no longer reversible. The target describes the protocol’s design; it is not a guarantee that every app will display settlement in that time. The handoff to Alpenglow took about 900 milliseconds, the Foundation reports.

What changes for payments and apps?

Faster finality could let services act on a payment or deposit sooner. CoinDesk reports that an exchange could credit a deposit earlier, while a merchant accepting stablecoins could confirm payment without making a customer wait for the network’s former finality period. How quickly the benefit appears in an app also depends on how that service receives and presents finality information.

For users, the Foundation says, signing and sending transactions remains the same: existing wallets and applications continue to work, and transaction formats, execution and fees are unchanged. The upgrade changes consensus, the process validators use to agree on the order of transactions and when blocks are final; it does not change how programs execute on Solana.

Why could transaction totals look different?

Under TowerBFT, validator votes were recorded as blockchain transactions. Alpenglow moves those votes off-chain, so they no longer count toward block transaction totals. CoinDesk reports that dashboards may therefore show lower totals even if user payments and trades have not fallen. Comparing activity across the upgrade requires separating user transactions from validator votes counted under the old system.

The Foundation says Alpenglow’s first phase, Votor, handles the new voting and finality process and is live on mainnet. A second phase, Rotor, is planned to replace Turbine, which spreads block data across the network, but has no scheduled release. For now, the user-facing change centers on faster finality; the core transaction and fee experience remains the same.

Sources

• Solana Foundation’s Alpenglow update — solana.com