multi region

Residency is not a checkbox on the primary datastore. Where bytes sit, who holds keys, and where logs, backups and analytics quietly replicate decide whether the deal signs.

Four tiers, four bills. Stating RTO and RPO per tier turns a vague resilience wish into a decision leadership can actually price, and the testing story is where candidates fold.

Active-active replication moves writes but not truth. Last-writer-wins quietly discards one of the two orders your finance team expects both to exist.

The design round where the honest answer is mostly about data. Stateless traffic across regions is straightforward; the database is where active-active is either solved or pretended.

DNS time-to-live is a suggestion and nineteen minutes is what believing it costs. The mechanism you choose decides your failover time, and the health check you choose decides whether it fires at all.

Data transfer appears on nobody's architecture diagram and reliably appears on the invoice. The strong answer enumerates the taxed flows, ranks the levers, and knows which tax is worth paying.

GPU capacity is not elastic the way CPU is. On-demand means whatever is left after the reservations, and in a tight region that is nothing, so the availability problem and the cost problem are the same problem.