Solana Sets Slot 459,653,000 as the Moment TowerBFT Retires

Solana's consensus rewrite now has a block height attached to it instead of a time. Anza, which maintains the network's main validator client, said on Tuesday that Alpenglow is pending activation on mainnet-beta, with the TowerBFT voting system it replaces retiring at slot 459,653,000. The handoff follows the start of epoch 1064 on Wednesday 21 October, after a countdown of about 5,000 slots. Target finality is roughly 150 milliseconds, finality being the point at which a transaction can no longer be undone. As of early Wednesday the switch had not happened, and the clock time attached to it is not one number.

One slot, and the clock is a projection

Anza named the boundary in a post at 12:25 UTC on 20 October, saying the new consensus "goes live tomorrow, Wednesday, Oct 21 at ~14:00 UTC". Its summary ran to six words.

"One slot, and TowerBFT retires," Anza said.

The accounts do not agree on when that slot arrives. Anza first set about 14:50 UTC, on 13 October. The Solana Foundation's upgrade page says epoch 1064 begins near 13:20 UTC, and Triton One used the same figure. Solana Compass, working from a 217.7-millisecond average slot in epoch 1062, puts the epoch start near 13:44 UTC and the boundary slot near 14:02, by its own arithmetic. CryptoSlate has it around 15:00. Two moments are being timed, the epoch start and the slot, and only the slot is fixed. Triton's advice was shorter: "Don't hard-code a date."

What a vote stops costing

Under TowerBFT every validator writes its votes on chain, as transactions that take up block space. Votor, the component activating now, moves that traffic off chain and folds many signatures into one certificate per slot. The savings figures do not reconcile. CoinDesk puts today's vote fees near 2 SOL a day and the flat validator admission ticket that replaces them at 0.8 SOL per epoch, calling that roughly 60% cheaper. Galaxy Digital's Solana engineers, on the test cluster since 18 June, give the same 0.8 SOL and call it less than half of the current bill. Tech Times, citing Alchemy, puts the daily vote cost at about 1.1 SOL and the cut at about 27%. The ticket is identical in all three accounts. What it is measured against is not.

Finality, measured from two baselines

The before-figure splits as well, and this one has an explanation. Most accounts give 12.8 seconds as current finality, Bankless and Tech Times among them. CoinDesk says about six seconds. Galaxy's engineers reconcile the pair: 12.8 seconds was the number at 400-millisecond slots, and roughly six seconds is the number since the network shortened slots to 200 milliseconds this month. The multiple moves with the baseline. CoinDesk calls the improvement 40-fold, Tech Times 85-fold.

Reported throughput will drop when the votes leave the ledger. That is an accounting change, not a slowdown. Compass network data has votes at about 62% of all Solana transactions between 13 and 19 October. Tech Times and Helius put the share nearer 75%. Robin Nordnes, chief executive of the Solana infrastructure firm Raiku, told CoinDesk by email that "most of what got counted before was validators voting, and that's off-chain now. The trading's all still there."

Who was still not ready on Tuesday

Readiness has been the open number. SolanaFloor, citing Pumpkin's Pool's tracker in a post at 10:59 UTC on 20 October, reported 151 validators holding 20.3% of stake still unprepared, against 45% of stake the same tracker flagged a day earlier. Most of the earlier figure was validators on Agave 4.3.0 and 4.3.1. The post does not say how the tracker now counts them, so we could not establish how much of the fall is real upgrading. Firedancer and Frankendancer operators sit outside that count, holding about 15.8% of stake by Tech Times's reckoning; those clients cannot join the genesis certificate vote, which needs 82%. Galaxy's engineers say slashing for double voting is defined but switched off in this first iteration. Devnet made the same switch in September, at slot 504148999. Triton One put it plainly: "There's no going back to the old consensus afterwards."