Solana Alpenglow mainnet launch aims for 150ms finality

Solana’s new Alpenglow consensus went live at slot 459,653,000 around 10 a.m. ET Wednesday, with a 150-millisecond finality target.

The Solana Alpenglow mainnet switch is done. Solana ($SOL) now runs on Alpenglow, a new consensus system, after validators moved off TowerBFT on Wednesday, Oct. 21. The Solana Foundation’s upgrade page now marks it “Live on Mainnet.”

The quick take

Price: $SOL trades at $108.26, up 1.6% in 24 hours (CoinGecko, as of 5:41 p.m. ET).
Trigger: Alpenglow replaced TowerBFT, Solana’s consensus system since 2020, on Wednesday.
Watch: How close live finality gets to the 150-millisecond target, and a date for Rotor.

What happened

The foundation says the change activated in epoch 1064, which began at about 9:36 a.m. ET (13:36 UTC). Alpenglow consensus runs from slot 459,653,000. The last block before it was certified by 446 of the network’s 654 validators.

Anza, Solana’s core engineering firm, put the handoff at about 10 a.m. ET (14:00 UTC), The Block and Decrypt report. Anza CEO Brennan Watt called it “the largest, most ambitious blockchain upgrade since ‘The Merge.'”

Finality is the point after which a transaction cannot be undone. Under TowerBFT that took about 12.8 seconds, the foundation says, and Alpenglow aims for about 150 milliseconds. Validators now trade votes with each other directly and group them into certificates, so one or two voting rounds can settle a block.

How transactions run does not change. Programs and fees stay the same, and wallets and apps should keep working as before.

What to watch next

Live numbers may trail the target at first. Cointelegraph reported that the foundation’s Alpenglow dashboard showed 6.6-second finality and 4,721 transactions per second at press time.

Rotor, the second phase, will change how block data spreads across the network. The foundation says it is planned for a later release and has no date yet.

Validator operators must run version 4.3.2 of Agave, Jito-Solana or Harmonic Salsa to keep voting. They also need a balance of at least 0.8 $SOL in their vote account to pay a new admission fee. Firedancer was not supported for the switch.

Bottom line: Alpenglow is now Solana’s consensus system, and the next test is how close live finality comes to its 150-millisecond goal.