reserved-instances

name	reserved-instances
description	Azure Reserved VM Instances — 1y vs 3y, scope, instance size flexibility, exchange/refund rules

Reserved Instances

When to use this skill

• Stable, steady-state workload running 24/7
• Long-term predictable capacity

Key concepts

• Scope: Single subscription / Shared / Management Group. Shared is most flexible.
• Instance Size Flexibility (ISF) — a D8s_v5 RI covers various D-series-v5 sizes in the same ratio group.
• Exchange rules have changed over time; verify current policy in Microsoft Learn before purchase.
• RIs are billed up-front or monthly (same total).
• Use Azure Advisor → Reservations for purchase recommendations based on history.

Azure CLI examples

# View existing reservations
az reservations reservation-order list -o table

# View utilization
az consumption reservation summary list-by-reservation-order \
  --reservation-order-id <id> --grain daily

Common pitfalls

• Buying RIs for a SKU that's about to be superseded (e.g. v4 right before v5 GA).
• Buying single-subscription scope when the org commonly moves workloads between subs.
• Forgetting RIs don't cover software (Windows/SQL) license — that's still PAYG unless AHUB is enabled.

References

• Microsoft Learn: search for "Reserved Instances Azure VM" on https://learn.microsoft.com

---

Validation-first: verify every Azure fact against the Microsoft Learn MCP server (cite the Learn URL); Learn overrides built-in knowledge. If no Learn MCP server is configured, flag the answer ⚠️ unverified and mark specs as indicative. Analysis only — verify against Microsoft documentation before applying.