A simulator can control timing, event ordering and modeled failures that would be hard to reproduce in a live distributed system. A recorded setup allows investigators to return to the same behavior while examining a suspected cause.
For example, a simulation can repeat a network delay that exposes a stale read. The result is evidence about the modeled scenario, not proof that every real-world condition is covered. The model and the range of explored cases remain important limits.
ELI5
Deterministic simulation lets you replay a modeled situation the same way. That makes it easier to study a problem that would otherwise happen unpredictably.
For example, a test can repeat the same delayed message until a developer understands why it caused an incorrect update.
Does deterministic mean no failures are simulated?
No. Failures can be deliberately included and reproduced as part of the controlled scenario.
Does simulation replace every real-system test?
No. The simulator's assumptions and modeled behavior may differ from actual hardware or deployment conditions.
