Solana activates Alpenglow, targeting 150ms finality

Solana activated Alpenglow on its mainnet on Oct. 21, replacing the TowerBFT consensus system with a new validator voting protocol that targets transaction finality in about 150 milliseconds. The change shortens the time applications wait before treating a transaction as irreversible. The Solana Foundation’s upgrade details say the network switched at the start of epoch 1064, at approximately 13:36 UTC.

How do validators reach finality faster?

Alpenglow’s first phase, Votor, changes how validators agree on blocks. Under TowerBFT, validators recorded votes as transactions on the blockchain, and a block became final after enough votes accumulated across 32 slots. With Votor, validators send votes directly to one another and combine them into certificates. A block can then become final after one or two rounds of voting, according to the Foundation.

The distinction is between a quick confirmation and finality: finality is the point when a transaction can no longer be reversed. Anza’s mainnet announcement says Alpenglow is designed to reduce that wait from about 12.8 seconds to roughly 150 milliseconds. The figure is a target, not a guaranteed time for every transaction or every user. CoinDesk reported that the time for finality information to reach a user’s device can vary.

What changes for apps and users?

Applications can treat payments as settled sooner, which may let an exchange credit a deposit or a merchant release a purchase earlier. The consensus change does not alter transaction execution: Solana’s programs, transaction formats and fees remain the same, and users can keep using their existing wallets.

Validator votes also no longer appear as on-chain transactions. Services that counted those votes in transaction totals may therefore show lower numbers after activation, even though those counts do not measure user payments and trades alone. Developers who stream or index block data may need to account for changes to how blocks and finality information are reported.

What is still due to change?

Alpenglow’s other planned phase, Rotor, is not yet scheduled. It is intended to replace Turbine, Solana’s block-data propagation system, with a relay layer. That work is separate from Votor’s live change to validator voting and finality.

The immediate change is that Solana’s mainnet now uses Votor, with finality targeted at about 150 milliseconds instead of roughly 12.8 seconds. The next milestone to watch is whether Rotor gets a release schedule; the Foundation says it has none yet.

References

• Solana Foundation’s upgrade details — solana.com
• mainnet announcement — prnewswire.com