Map a complete request through Helsinki
Draw the path of a representative operation, such as signing in or saving a document. Where are the database, cache and external API used by that operation? Measure each stage so an apparently slow Finnish server is not confused with a distant dependency or application bottleneck.
Place the busiest dependencies deliberately
Keep frequently repeated application-to-database calls in mind when choosing placement. A cache can reduce repeated reads, but it also needs an invalidation and recovery plan. Which data must be current, and which responses can safely be reused? Confirm the available private connectivity before designing around it.
Test a cache miss and an unavailable API
A warm cache can hide the cost of the first real request. Test after a restart, with an empty cache and with an external service timing out. Set bounded retries and check that a repeated request does not create a duplicate operation. These cases make the Helsinki deployment easier to size realistically.
Make backup placement part of the restore test
Another machine in the same facility is not a geographic recovery plan. Record the actual backup destination and restore a sample outside the primary failure boundary. After recovery, check database connections, application secrets and cache rebuilding before sending users to the restored service.