If the region germanywestcentral fails, the booking portal of Nordlicht Reisen GmbH stops, and two Windows servers in Hamburg depend on services that are then missing. This lesson chooses what Nordlicht Reisen keeps working with after a region outage: for data in Azure, for compute and for servers that stay on site.
Prior knowledge. RTO and RPO, geo-restore and failover groups of Azure SQL, and the test are taught by K4, lesson 4.7.5; Azure Site Recovery for Azure VMs with test failover by AZ-104, lesson 5.6; backup by lesson 3.1 of this course. None of that is repeated. What is new is the choice between the means and the question of which region to fall back to.
The requirement
Numbers are assumptions of the task.
| No. | Requirement | Source | Measure (assumption) |
|---|---|---|---|
| N1 | Booking database survives the outage of the region | Management | RPO 5 minutes, RTO 1 hour |
| N2 | Portal (web and app) reachable | Sales | RTO 1 hour |
| N3 | Two Windows servers in Hamburg fail (site, power) | Operations | RTO 8 hours, RPO 24 hours |
| N4 | Files (lesson 2.4 of this course) stay reachable | Operations | RTO 8 hours |
| N5 | Everything in the EU | Data protection | Base assumption |
The region outage is a scenario of its own: a zone outage is covered by high availability (lessons 3.3 and 3.4), deletion and wrong data by backup (lesson 3.1). Redundancy copies errors into every copy.