Real

Solana

when

Alpenglow, a new consensus protocol built by Anza (<a href="https://x.com/anza_xyz" rel="noopener noreferrer nofollow">@anza_xyz</a>), went live on <a href="https://x.com/solana" rel="noopener noreferrer nofollow">@solana</a> mainnet on October 21, replacing the TowerBFT system the <a href="https://x.com/search?q=%24SOL&amp;src=cashtag_click" rel="noopener noreferrer nofollow">$SOL</a> network has run since launch. Anza says it is designed to cut finality from about 12.8 seconds to roughly 150 milliseconds.
<cite>Anza CEO Brennan Watt called it the largest, most ambitious blockchain upgrade since "The Merge," taken from a white paper to mainnet in under 18 months.</cite><cite>A total of 654 validators participated in the transition, which took 900 milliseconds, according to TechFlow.</cite>
<h2 id="what-changes-for-solana">What changes for Solana</h2>
<cite>The deployment retires TowerBFT, the consensus protocol Solana had operated since its March 2020 launch,</cite><cite>and Anza said Alpenglow reached mainnet-beta at slot 459,653,000.</cite><cite>The change condenses Solana's previous two-step transaction confirmation process into a single step, according to Anza, which it says matters for exchanges crediting deposits and merchants processing payments.</cite>
Finality is the point at which a transaction can no longer be reversed. <cite>Alpenglow's first component, Votor, changes how validators agree on blocks and removes the vote transactions that made up most of Solana's on-chain traffic.</cite><cite>Under the design, a block is finalized in one round if 80% of stake responds, or after two rounds at 60%, Anza said.</cite>
The upgrade also changes how much faulty stake the network can tolerate. <cite>Alpenglow tolerates up to 20% adversarial stake and a further 20% offline stake, so the network can lose 40% of stake to faults and keep running.</cite>
<h2 id="speed-figure-is-still-a-target">Speed figure is still a target</h2>
The 150 millisecond number comes from Anza and should be treated with some caution for now. <cite>Solana Compass noted the figure is Anza's own and that no independent post-switch measurement had been published when its article went out.</cite><cite>CoinDesk reported ahead of the launch that the figure remains a target, with actual performance depending on network conditions.</cite>
<cite>CoinDesk also noted that moving validator votes off-chain could sharply reduce Solana's reported transaction count without reflecting a decline in user activity.</cite> Analysts and traders comparing on-chain activity before and after the switch may need to account for that.
Anza has said it expects the upgrade to matter most to exchanges, banks and merchants that depend on fast settlement. Real mainnet data over the coming weeks will show how close the network gets to its target.
Sources:
<ul>
 <li><a href="https://www.theblock.co/news/ecosystems/2026-10-21-anzas-alpenglow-goes-live-on-solana-cutting-finality-to-150-milliseconds-421508" rel="noopener noreferrer nofollow">The Block: Anza's Alpenglow goes live on Solana, cutting finality to 150 milliseconds</a></li>
 <li><a href="https://solanacompass.com/news/solana-alpenglow-is-live-on-mainnet-as-anza-retires-towerbft-at-slot-459653000" rel="noopener noreferrer nofollow">Solana Compass: Alpenglow is live on mainnet as Anza retires TowerBFT</a></li>
 <li><a href="https://www.coindesk.com/tech/2026/10/14/solana-sets-oct-21-for-alpenglow-upgrade-targeting-150-millisecond-finality" rel="noopener noreferrer nofollow">CoinDesk: Solana sets Oct. 21 for Alpenglow upgrade targeting 150-millisecond finality</a></li>
</ul>

Solana switches on Alpenglow, built to settle trades in a blink

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