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Solana activates Alpenglow, with 150ms finality still a target

Solana activated Alpenglow on Oct. 21, replacing TowerBFT with a consensus system targeting 150ms finality, while early independent measurements put observed finality near 404ms.

Uruguay Can Editorial

Solana activates Alpenglow, with 150ms finality still a target

Solana had used TowerBFT consensus since its 2020 launch; on Oct. 21, validators replaced it with Alpenglow on mainnet, Anza said in its announcement that the upgrade had gone live. The new protocol targets transaction finality in about 150 milliseconds, a change meant to shorten the wait before payments and exchange deposits are settled.

What changed when Alpenglow went live?

The switch happened at slot 459,653,000, at about 14:00 UTC, according to Anza. It retired TowerBFT and replaced Solana’s previous two-step confirmation process with a system designed to finalize blocks in one or two voting rounds. For you as a user, the aim is quicker certainty that a transaction will not be reversed; the change is to how validators reach agreement, not to how wallets submit transactions.

How do validators reach finality now?

Alpenglow’s first phase, Votor, lets validators exchange votes directly and combine them into certificates, rather than recording those votes as on-chain transactions. That cuts a layer of delay from the consensus process. The protocol’s 150ms figure is a target, though, and it should not be read as a measured time for every user or transaction.

What finality are users seeing so far?

An independent OpenChainBench measurement published Oct. 23 put the median at 404 milliseconds over the prior 24 hours, based on more than 357,000 slots. Its measurement tracked when a public RPC node first reported a slot and when it reported that slot rooted, so it includes the node’s own processing time. That is slower than Anza’s protocol target, but still below half a second at the median in that sample.

The gap matters when you compare the headline target with the wait visible from outside the validator network. Alpenglow has made sub-second finality the live network’s direction; the early independent reading gives you a more grounded sense of what an RPC client observed just after activation. A later Alpenglow phase, Rotor, is intended to change block propagation, but no release date was confirmed in the sources reviewed.

Sources