Which application architecture model is most disruptive in the event of a failure?

Standalone Architecture is considered the most disruptive in the event of a failure because it operates independently as a single unit. If a failure occurs in a standalone application, it completely halts the functionality for that user or system, leading to an immediate impact on productivity and operations. Since there are no additional layers or components to mitigate the failure (like in tiered architectures), any problems in the standalone system directly lead to an outage of services.

In contrast, multi-tier architectures, such as two-tier, three-tier, and n-tier models, are designed with layers that can provide fault tolerance and redundancy. For instance, if one part of a n-tier architecture fails, other components may continue to operate, allowing for some degree of functionality, which minimizes disruption. Thus, while a failure in a standalone system can bring entire operations to a stop, tiered architectures often have built-in mechanisms to reduce the impact of failures.