Solana activates Alpenglow, targeting 150ms transaction finality

Solana activated Alpenglow on its mainnet on Oct. 21, replacing the validator voting system it has used since launch and targeting faster transaction finality for users, according to the Solana Foundation’s Alpenglow upgrade page. The target is about 150 milliseconds, down from roughly 12.8 seconds under the previous system.

Finality is the point at which a transaction can no longer be reversed. Solana’s validators—computers that process transactions and agree on the network’s state—must reach consensus before a block is final. The change affects how they reach that agreement; it does not change how transactions execute.

How does Alpenglow change validator voting?

Under the old TowerBFT system, validators recorded their votes as transactions on the blockchain. Enough votes had to accumulate over 32 slots before a block became final, the Foundation says.

Alpenglow’s live voting protocol, Votor, moves those votes off-chain. Validators send votes directly to one another, then combine them into certificates. A block can become final after one or two rounds of voting, instead of waiting for votes to stack up on-chain. CoinDesk’s report on the activation also describes the shift to off-chain voting and the roughly 150-millisecond target.

The target describes how quickly a transaction becomes final, not how often Solana produces blocks. The Foundation says block production and transaction execution remain separate from this change.

What changes for people using Solana?

For users, the main potential benefit is a shorter wait before a transaction is settled. That could help wallets, exchanges and payment services treat transactions as final sooner. The 150-millisecond figure is a target; actual finality depends on network conditions.

Users do not need to switch wallets or change how they send transactions. The Foundation says the upgrade leaves the Solana Virtual Machine, transaction formats, programs and fees unchanged. Applications that only send transactions and read account data do not need to migrate.

What changes for validators and network data?

Validator operators do have new requirements. They 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 their vote account to pay a fee each epoch. The Foundation says validators that do not pay cannot vote or produce blocks in the following epoch.

Because validator votes no longer appear as on-chain transactions, headline transaction counts and dashboards that included those votes will fall. That drop does not, by itself, mean users are making fewer transactions.

Alpenglow is rolling out in two phases. Votor, which changes voting and finality, is live. Rotor, a planned later phase, is intended to replace Turbine, Solana’s block-data distribution protocol; the Foundation says it has not yet been scheduled.

Sources

• Solana Foundation’s Alpenglow upgrade page — solana.com
• CoinDesk’s report on the activation — coindesk.com