COMMON FOUNDATION / M01

Requirements Engineering & Quantitative Estimation

Master back-of-the-envelope calculations, system constraints, latency hierarchies, and availability budgets.

2 topics60 min estimatedPublished

System design is fundamentally about making engineering trade-offs under physical and operational constraints. Before choosing technologies, drawing service boundaries, or selecting database engines, an engineer must know the scale and constraints of the problem.

This module provides the mathematical and quantitative toolkit required for all architecture decisions:

  1. Back-of-the-Envelope Estimation: Transforming user activity and business requirements into concrete queries-per-second (QPS), network bandwidth, storage growth, and memory caching budgets.
  2. Availability & Reliability Math: Defining Service Level Indicators (SLIs), Service Level Objectives (SLOs), and Error Budgets, and calculating composite availability across serial and redundant components.
  3. Failure Domain & Peak Headroom Modeling: Quantifying peak-to-average traffic ratios, correlated versus independent failure probabilities across availability zones, and the operational burn-rate alerts that govern safe production velocity.

What you will learn

  • Translate vague business requirements into concrete engineering numbers
  • Calculate storage, throughput, memory, and bandwidth requirements under peak conditions
  • Recall the hardware and network latency hierarchy that dictates system performance
  • Model service availability, downtime budgets, and error budget burn rates
STAGE TOPICS

Topics in this chapter

Step 02Back-of-the-Envelope EstimationLearn quantitative reasoning to size compute, storage, throughput, and network bandwidth for scaled systems.25 min ↗Step 03Availability, SLOs, and Downtime BudgetsLearn the mathematics of high availability, downtime budgets, SLIs/SLOs, and composite system reliability.25 min ↗