How it works

Availability, distribution and backups

Vertical scaling increases CPU or RAM; horizontal scaling adds app copies. Protection against a host failure requires copies on different hosts, suitable routing and spare capacity. Applications run in the USA and in Germany; Brazil is CDN cache only and does not run apps.

Database replication and failover are a separate data-service configuration. Backups recover earlier data; replication maintains operational copies. Neither application replicas nor database replication alone promise zero downtime in every failure.