SRE Cost Optimization and Cloud Resource Management

Question 1

What is 'cloud cost optimization' in the SRE context, and why is it part of SRE's responsibilities?

Accepted Answer

Cloud cost optimization ensures that infrastructure resources are right-sized and efficiently utilized, supporting reliability goals by preventing resource waste that could be invested in redundancy, monitoring, and DR capabilities

Answer

SREs own infrastructure efficiency as part of service ownership — over-provisioned services waste budget that could fund reliability improvements, while under-provisioned services create reliability risks. Cost and reliability are two dimensions of the same resource allocation decision.

Question 2

What is 'right-sizing' in cloud infrastructure, and what data is needed to do it effectively?

Accepted Answer

Right-sizing matches instance types and sizes to actual resource consumption by analyzing CPU, memory, and I/O utilization metrics over time, selecting the smallest instance that provides adequate headroom for peak load and scaling events

Answer

Right-sizing requires historical utilization data to identify instances that are significantly over-provisioned (average CPU <20%, memory <30%) and to determine the appropriate size that provides performance headroom without excessive waste.

Question 3

What are 'reserved instances' (RIs) or 'committed use discounts' (CUDs), and when should SREs recommend them?

Accepted Answer

Reserved instances are pre-purchased cloud compute commitments (typically 1-3 years) that provide 30-70% cost savings over on-demand pricing in exchange for committing to a minimum usage level — appropriate for stable, predictable baseline workloads

Answer

RIs provide significant cost savings (often 40-60%) for stable workloads in exchange for a usage commitment. They are appropriate for services with predictable, stable resource needs — not for development environments or highly variable workloads.

Question 4

What are 'spot instances' (AWS) or 'preemptible VMs' (GCP), and what type of workloads are they MOST suitable for?

Accepted Answer

Spot/preemptible instances are deeply discounted (70-90%) cloud compute that can be reclaimed by the provider with short notice; they are most suitable for fault-tolerant batch workloads like data processing, rendering, and CI/CD workers that can be safely interrupted and restarted

Answer

The 2-minute reclamation notice means spot/preemptible instances are unsuitable for stateful production services or real-time user-facing workloads. They excel at fault-tolerant batch jobs that checkpoint progress and can restart from a checkpoint when preempted.

Question 5

What is 'resource tagging strategy' in cloud cost management, and why is it important for SRE teams?

Accepted Answer

Resource tags (key-value pairs on cloud resources) enable cost allocation by service, team, environment, and owner — allowing SREs to identify cost anomalies, enforce accountability, and make data-driven right-sizing decisions per service

Answer

Without consistent tagging, cloud costs appear as undifferentiated infrastructure spend. Tagging enables per-service, per-team cost visibility — essential for identifying which services are expensive, which teams are over-provisioned, and where optimization has the most impact.

(SRE) Site Reliability Engineering Foundation Certification Practice Test

(SRE) Site Reliability Engineering Foundation Certification Practice Test

SRE Cost Optimization and Cloud Resource Management