Underutilized VM Commitments Due to Architectural Drift

Diana Lezcano

Service Category

Compute

Cloud Provider

GCP

Service Name

GCP Compute Engine

Inefficiency Type

Underutilized Commitment

Explanation

VM-based Committed Use Discounts in GCP offer cost savings for predictable workloads, but they are rigid: they apply only to specified VM types, quantities, and regions. When organizations evolve their architecture — such as moving to GKE (Kubernetes), Cloud Run, or autoscaling — usage patterns often shift away from the original commitments. Because GCP lacks flexible reallocation options like AWS Convertible RIs or Savings Plans, underutilized commitments lead to sustained, silent waste. This is especially common when workload changes go uncoordinated with finance or centralized planning.

Relevant Billing Model

CUDs are billed based on committed resource quantities (e.g., vCPUs, memory) for specific VM families and regions, regardless of actual usage. If consumption falls below the commitment level, the unused portion is still billed, generating cost with no value returned.

Detection

Review actual usage against committed VM types and regions across a representative time period
Identify consistent underutilization of CUDs based on usage-to-commit ratio
Confirm whether architectural shifts (e.g., to GKE, Cloud Run, or autoscaling groups) have occurred
Check for commitments applied to workloads that have been decommissioned or scaled down
Evaluate whether commitments are isolated to specific projects, regions, or teams without visibility across the org

Remediation

Consolidate workloads onto committed VM types where feasible
Avoid renewing commitments for workloads that are scaling down or migrating
Use Resource-based CUDs when architectural flexibility is needed
Implement cross-functional governance for forecasting and commitment approvals
Align future commitments with current and expected usage patterns, not historical ones

Relevant Documentation

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