Solana Activates Alpenglow, Targeting 150ms Finality

Anza activated Alpenglow on Solana on Oct. 21, replacing TowerBFT and targeting transaction finality in about 150 milliseconds, down from 12.8 seconds. In its announcement distributed by PR Newswire, Anza said validators made the switch at slot 459,653,000 and that transactions now become irreversible in about 150 milliseconds.

Finality is the point when a transaction can no longer be reversed. It tells an exchange or merchant when it can treat a transfer as settled. Alpenglow changes how Solana validators reach that point: the computers that process transactions also agree on which blocks are valid.

How does Alpenglow reach finality faster?

Under TowerBFT, validators recorded their votes on the blockchain as transactions. Alpenglow moves those votes off-chain. Validators send votes directly to one another, then bundle them into certificates that show agreement. As CoinDesk reported in its explanation of the upgrade, a certificate can lock in a block in one or two voting rounds.

The certificate works like a signed tally: it lets validators establish that enough stake approved a block without writing each vote into the chain. Anza describes the new process as condensing the previous two-step path to finality into one. That removes the wait for votes to accumulate on-chain and reduces the time between a block being proposed and its settlement.

What does the 150-millisecond figure mean?

Anza gives about 150 milliseconds as the new finality time, compared with 12.8 seconds under TowerBFT. It is a target, not a fixed time for every block. CoinDesk reported the figure as an expected result; actual timing depends on validators completing the voting rounds. A faster finality time means applications can know sooner that a transaction is settled.

That timing refers to finality, not the time it takes to produce a block. The two measures describe different steps: block production puts transactions into a candidate block, while finality is the network’s agreement that the block cannot be reversed.

What changed for Solana validators?

Validators retired TowerBFT and moved the live network to Alpenglow while carrying Solana’s existing ledger forward, Anza said. Anza developed the protocol and implemented it in Agave, its validator software; independent validator operators adopted and activated the upgrade.

The switch changes how validators vote and settle blocks. Anza said transaction execution remains part of the network’s existing system, while further Alpenglow-related changes to block-data distribution are planned for later releases without a committed date. For users, the immediate change is the time the network takes to treat a transaction as final.

Source material

• announcement distributed by PR Newswire — prnewswire.com
• CoinDesk reported in its explanation of the upgrade — coindesk.com