Expert
A ledger that outlives its region
A North American payments company already serves traffic from Virginia and Montréal behind a global load balancer. Its ledger, a distributed SQL cluster, still runs entirely in Virginia. At 14:00 Virginia goes dark for three hours, and at 15:30 a ledger node crashes while the region is still down. Keep every payment flowing.
The ledger is one logical database: you may reconfigure it but not replace it, and no payment may be answered with a fallback. It commits every write through Raft, so a write needs a majority of the nodes. A crashed node restarts on its own after a few minutes.
What your design must achieve
- Availability ≥ 99.95 %
- Latency p99 < 300 ms
- Lost writes = 0