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02. Rate Optimization: RIs, Savings Plans, CUDs, and Private Pricing

The Rate Optimization Stack

Rate optimization is the collective set of mechanisms that reduce unit price without changing usage. The stack has layers:

  1. Public on-demand pricing (the default)
  2. Volume or tier discounts (automatic at scale)
  3. Commitment-based discounts (RIs, SPs, CUDs)
  4. Spot and preemptible pricing (for interruptible workloads)
  5. Private pricing agreements (EDP, MACC, custom)
  6. Marketplace and resale pricing

Rate Optimization as a FinOps capability deals primarily with layers 3, 4, 5. Usage and architectural moves live in other capabilities.

AWS Rate Optimization Instruments

Reserved Instances (RIs)

  • Standard RI: largest discount (up to ~72 percent), tied to instance family/region, shareable across accounts
  • Convertible RI: smaller discount (up to ~54 percent), allows family changes
  • RI term: 1 or 3 years; payment: All Upfront, Partial Upfront, No Upfront
  • Scope: regional (flexible AZ) vs zonal (capacity reservation)
  • Mostly superseded by Savings Plans for EC2 compute, still relevant for RDS, ElastiCache, OpenSearch, Redshift

Savings Plans (SPs)

  • Compute SP: most flexible; applies to EC2, Fargate, Lambda; instance family-agnostic
  • EC2 Instance SP: instance family specific, higher discount
  • SageMaker SP: SageMaker training and inference
  • Commit: dollars per hour, not units
  • Auto-applied against highest-discount-eligible usage

Private Pricing

  • EDP (Enterprise Discount Program): multi-year spend commit for an AWS-wide discount, typically 5-15 percent
  • PPA (Private Pricing Agreement): service-specific negotiated rates
  • Support tier discounts: Business/Enterprise/Enterprise On-Ramp

Azure Rate Optimization Instruments

  • Reservations: 1 or 3 year; compute, SQL DB, Cosmos DB, Storage, and more
  • Azure Savings Plan for Compute: similar to AWS Compute SP; commits hourly spend for compute flexibility
  • Azure Hybrid Benefit: BYOL for Windows/SQL with Software Assurance
  • Spot VMs: interruptible capacity discount
  • Azure Consumption Commitment (MACC): multi-year spend commit for Azure-wide discount
  • Enterprise Agreement (EA) and Microsoft Customer Agreement (MCA): contract frameworks

GCP Rate Optimization Instruments

  • Resource-based CUDs: commit to specific instance types in a region; up to ~57 percent discount; 1 or 3 year
  • Spend-based CUDs: commit to a dollar amount across compute SKUs; more flexibility, lower discount
  • Flexible CUDs: even broader flexibility across machine types
  • Sustained Use Discounts: automatic monthly discount for running instances; automatic, no commitment
  • Custom CUDs: negotiated for large customers
  • Spot VMs / Preemptible: interruptible capacity discount

The Commitment Decision Tree

Given a workload, ask:

  1. Is the usage stable enough to commit? (look at 90-day floor, not average)
  2. How likely is architectural change in the next 1-3 years?
  3. Is the workload interruptible? (spot first for these)
  4. Does the provider offer a flexible commit (Compute SP, flexible CUD)?
  5. Is the commit term aligned with business planning horizons?
  6. Is there a central pool that can absorb unused commit risk?

Coverage Targets

Aim for coverage below the stable usage floor, not at the mean.

  • Stable mature workloads with low migration risk: 70-85 percent coverage, 1-3 year mix
  • High-change environments: 50-65 percent coverage, 1 year terms
  • New workloads (less than 6 months of history): do not commit yet

The Effective Savings Rate (ESR)

ESR = (ListCost - EffectiveCost) / ListCost

It integrates all rate sources: volume, commitments, private pricing, spot. A healthy ESR varies by industry and workload mix:

  • Steady-state enterprise AWS: 25-35 percent typical
  • Aggressive spot-heavy: 40 percent+
  • New cloud adopters: 10-15 percent
  • Greenfield with mostly managed services: lower (less commit-eligible)

Track ESR monthly. Target a specific ESR, not just a coverage number; coverage without utilization is a loss.

Convertible vs Standard: When It Matters

Convertible RIs and Compute SPs are superior when:

  • Architectural change is expected
  • Instance family evolution is likely (Graviton migration)
  • Business unit usage will shift across products

Standard RIs and EC2 Instance SPs win when:

  • Usage pattern is fixed for 3 years
  • Maximum discount is the priority
  • There is a central pool to absorb mismatch

Autonomous Commitment Platforms

ProsperOps, Zesty, Spot.io Commitments manage the commitment portfolio continuously: laddered short-term commits, exchanges where allowed, and a target ESR. They typically earn their fee for orgs over 10M AWS spend.

Trade-offs:

  • Pro: measurable ESR improvement, removes renewal anxiety, continuous optimization
  • Con: ongoing fee (often percent of savings), less visibility into individual commits, provider-specific

Private Pricing Negotiation

EDPs, MACCs, and equivalent are negotiated contracts. Key levers:

  • Multi-year term (2-5 years typical)
  • Spend commitment (with true-down provisions if possible)
  • Specific service discounts (custom SKUs)
  • Professional services credits
  • Marketing or case study value
  • Co-terminus end dates

Never negotiate in the last quarter of a contract; vendors know. Start 6-9 months ahead.

Common Exam Traps

  • Confusing coverage and utilization
  • Assuming higher coverage is always better
  • Picking Standard RI in a migration scenario
  • Ignoring Compute SP flexibility advantage
  • Mixing up EDP (spend commit for discount) with MACC (Azure equivalent)
  • Forgetting sustained use discounts are automatic in GCP (not a commit)
  • Recommending commits for new workloads without 90+ day history