According to developer Wietse Wind, the XRP Ledger stopped processing transactions for roughly 15 minutes earlier today.
For validating new ledgers, each protocol server has its own unique node list (UNL). The quorum threshold is set at 80% of the total membership. The network is unable to confirm new transactions if more than 20% of validators cannot reach consensus or stay unreachable. Four validators were offline, according to Wind, causing the quorum to fall below the needed level.
A new ledger’s typical close time is roughly four seconds, but validators were unable to reach a consensus, halting transaction processing.
Update: it lasted not 2 minutes (my original Tweet) but 15 minutes. At the time of Tweeting (because I have decent monitoring and was warned straight away) the counter was at 2 minutes missing forward progress.Also: 4 validators down: this was caused by a lot more being down.— WietseWind – 🛠XUMM @ XRPL Labs (@WietseWind) November 3, 2021
This is what the ledger close times look like (courtesy of @Silkjaer). From UTC 12:25 » 12:48 validators couldn’t agree on what should have been included in the next ledger. pic.twitter.com/MJMD4Bb2lh— WietseWind – 🛠XUMM @ XRPL Labs (@WietseWind) November 3, 2021
A spokesperson for the XRP Ledger Foundation believes that the mishap did not result in any transactions being lost.
As we are aware the XRPL choses safety over liveliness. There was a temporary halt in ledgers closing. There were no ledgers dropped, or holes created. Validators are proposing now, nodes are active and the network is back on track with no intervention.— XRP Ledger Foundation (Official) (@XRPLF) November 3, 2021
Following a brief halt, Wind reports that the network is now operational as usual:
Finally: your XRP is safe. No history is lost, the XRPL is working. I believe we need more proactive infrastructure operators.
As Ripple‘s chief technology officer, David Schwarz was supportive of the implementation of the Negative UNL feature, which assures that the network can continue to make forward movement even while multiple validators are unavailable. Transactions would continue to be confirmed in this manner even if there was a momentary outage.
We need to get the negative UNL feature deployed. More validators is also good, but has some of its own tradeoffs.
