Capacity Planning & Scaling Flashcards
7 cards from real SRE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Capacity Planning & Scaling flashcards as text
What is 'graceful degradation' in the context of capacity planning?
Answer: Reducing feature functionality under overload rather than failing completely
Graceful degradation means intentionally shedding non-critical functionality under excess load to preserve core service availability and user experience.
An SRE team uses the 'four golden signals' for capacity-related alerting. Which signal most directly indicates imminent capacity exhaustion?
Answer: Saturation
Saturation measures how full a resource is (CPU, memory, disk, network), making it the most direct indicator that capacity is being exhausted.
Which technique allows a team to test system behavior under 2× production load without generating real user traffic?
Answer: Shadow traffic (dark launch) mirroring
Shadow traffic mirrors real production requests to a parallel environment, allowing load testing at scale with real patterns without impacting users.
In vertical scaling, what is the primary limitation compared to horizontal scaling?
Answer: There is a hardware ceiling beyond which a single machine cannot be scaled further
Vertical scaling is bounded by the largest available hardware instance, whereas horizontal scaling can theoretically add unlimited nodes.
What is 'traffic shaping' used for in capacity management?
Answer: Controlling the rate and distribution of incoming requests to protect backend capacity
Traffic shaping uses rate limiting, queuing, and throttling to control request flow so backends are not overwhelmed beyond their capacity.
A team's capacity plan assumes 20% year-over-year traffic growth, but actual growth is 60%. What SRE process failure does this indicate?
Answer: Poor demand forecasting and failure to review forecasts against actuals
A large gap between forecast and actual growth indicates the demand forecasting process lacked accuracy and regular calibration against real traffic trends.
Which capacity planning concept describes the point where adding more resources produces diminishing or negative returns due to coordination overhead?
Answer: Universal Scalability Law (USL) retrograde region
The Universal Scalability Law models throughput vs. concurrency and predicts a retrograde region where coordination costs cause throughput to decrease with more resources.