4ROUTER / Reliability
Keeping workloads isolated
Separating resources, data and failure domains.
Engineering note
Isolation is more than a quota
Concurrency and resource limits constrain consumption; they do not establish a complete security boundary. Caches, filesystems, network access, accounts and logs may cross workloads. Define each boundary against data sensitivity and deployment needs.
Contain the failure domain
Resource exhaustion should be identifiable and its impact bounded. Timeouts, queues, cancellation and reclamation work together. Shared replicas, separate processes and separate nodes provide different isolation boundaries with different costs.
Test the intended boundary
Test excessive demand, crashes, cache cleanup and denied access as well as normal calls. Private deployments also need checks on model files, telemetry egress and backups. Deployment location alone does not describe every data-protection control.
Before implementation
- Resource and data boundaries
- Network egress and permissions
- Crash and cleanup tests
