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Chapter 5 · Optimizing performance and cost·v1.0.0·Updated 6/15/2026·~13 min

What's changed: Created Professional Cloud DevOps Engineer Chapter 5 (Domain 5 "Optimize": APM performance collection, Active Assist insights/recommendations, recommenders (cost/security/performance/manageability/reliability); FinOps = Spot VMs/CUD/SUD/network tiers, utilization/rightsizing, observability cost, per-workload optimization for GKE/Cloud Run/Compute Engine).

5.2FinOps and optimizing workload costs

Key points

Understand FinOps practices: Spot VMs, committed-use discounts (CUD) and sustained-use discounts (SUD), network tiers, optimizing resource utilization, observability costs, leveraging recommenders, and optimizing GKE/Cloud Run/Compute Engine workload costs.

FinOps is the culture and practice where engineering and finance collaborate to continuously optimize cloud cost. Combine discounts, purchase options, and utilization to cut waste while preserving SLOs.

5.2.1Discounts, purchase options, and network tiers

LeverKey point
Spot VMsDeep discount, preemptible—for fault-tolerant/batch
Committed-use discounts (CUD)Commit 1/3-year usage for a discount
Sustained-use discounts (SUD)Automatic discount for sustained use
Network tiersPremium/Standard trade performance vs cost

Run fault-tolerant/batch workloads that tolerate interruption on Spot VMs for deep discounts. Lower steady capacity with committed-use discounts (CUD) (1/3-year commitments); sustained-use discounts (SUD) apply automatically to long-running resources. Choose egress network tiers (Premium/Standard) to trade performance vs cost. Map "interruptible batch = Spot VMs" and "steady-use discount = CUD."

5.2.2Utilization and per-workload optimization

Raise resource utilization and trim over-allocation via rightsizing (using recommenders). Reduce observability cost with log filtering/exclusions and metric cleanup. Per workload: optimize GKE with cluster autoscaler/node pools/container rightsizing, Cloud Run via request billing and min instances tuning, and Compute Engine by combining machine type/CUD/Spot. The principle is to cut only without sacrificing SLOs. Map "measure and trim waste = utilization + rightsizing."

Exam point

Common: requirement → means. E.g., "cheap interruptible batch" = Spot VMs; "discount steady use via 1/3-year commit" = CUD; "automatic discount for long use" = SUD; "egress performance/cost choice" = network tiers; "rightsize oversized instances" = rightsizing; "lower log cost" = filtering/exclusions.

Warning

Watch the mix-ups: (1) Spot VMs can be preempted—not for stateful, availability-critical prod. (2) Do not confuse CUD (pre-committed discount) with SUD (automatic sustained discount). (3) Do not breach SLOs when cutting cost (reliability trade-off).

Diagram of Spot VMs (interruptible batch)/CUD (commit)/SUD (automatic)/network tiers, raising utilization and rightsizing/observability cost, and per-workload optimization for GKE/Cloud Run/Compute Engine within SLOs.
Cut within SLOs

5.2.3Section summary

  • Discounts = Spot VMs (interruptible batch)/CUD (commit)/SUD (automatic); egress via network tiers
  • Raise utilization; trim waste via rightsizing and observability-cost optimization (log filtering/exclusions)
  • Per workload = GKE (autoscaler/node pools)/Cloud Run (min instances)/Compute Engine (machine type/CUD/Spot); preserve SLOs

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Quick check

(just a quick review)

Q1. To run interruptible batch workloads at a deep discount, which is best?

Q2. To discount steady capacity via a 1- or 3-year commitment, which is best?

Q3. Which discount applies automatically to resources used for a sustained period?

Q4. To resize over-allocated instances to match actual usage, what is this called?

Q5. To reduce observability (log) cost, which measure is best?

Q6. What constraint must you always uphold when optimizing cost?

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