Solana activates Alpenglow, targeting 150ms finality

Solana activated Alpenglow on its main network on Wednesday, October 21, replacing its consensus protocol with a new system that targets transaction finality in about 150 milliseconds, according to The Block’s report on Anza’s announcement. Finality is the point when an app can treat a transaction as settled.

• Target finality: about 150 milliseconds.
• Previous finality: 12.8 seconds, according to Anza.
• Activation point: slot 459,653,000, at about 14:00 UTC.

The change, called Alpenglow, retires TowerBFT, the protocol Solana used since its March 2020 launch. It matters most when a service needs confidence that a payment or deposit has settled before it releases funds, goods or a trade.

How does Alpenglow speed up settlement?

Alpenglow changes how validators—the computers that check transactions and agree on the network’s records—vote on blocks. Instead of recording their votes as blockchain transactions, validators exchange votes directly and combine approvals into certificates, according to CoinDesk’s report on the upgrade.

That lets a block become final after one or two voting rounds. The older process took longer because it gathered approvals across successive blocks. The upgrade condenses the previous two-step confirmation process into one, Anza told The Block.

CoinDesk reports that the 150-millisecond figure is a target under normal network conditions, not a guaranteed wait for every transaction. How quickly the result appears to you also depends on the app or service handling it; some computers receive finality information later than validators do.

What could change for payments and deposits?

Exchanges could credit deposits sooner, so you can trade with funds sooner after sending them. Merchants accepting stablecoins could also get stronger assurance that a payment has settled before handing over goods or releasing a service.

Some Solana apps already showed transactions as confirmed before the network had fully finalized them. Alpenglow aims to shorten the remaining wait, giving those apps a faster point at which to treat a payment as settled. CoinDesk says wallets, fees and applications remain unchanged, so users can keep their existing wallets.

The benefit depends on services using the faster finality in their own payment and deposit systems. The network’s target does not, by itself, guarantee that every exchange or merchant will update its process or show confirmation in 150 milliseconds.

Why might Solana transaction charts show a drop?

Alpenglow takes validator votes off-chain, so they no longer count as blockchain transactions. That can make transaction totals on some dashboards fall even if users are still making the same number of payments and trades, CoinDesk reports.

The change affects how those totals should be read. A chart that counted validator votes alongside user activity may show a sharp drop after the upgrade, without that drop representing an equivalent fall in user transactions.

Sources and documents

• The Block’s report on Anza’s announcement — theblock.co
• CoinDesk’s report on the upgrade — coindesk.com