Reserved Instances
Reserved Instances (RIs) provide significant discounts (up to 72%) on AWS services in exchange for a commitment to a specific instance configuration over a one- or three-year term. Guardian Pro's RI management capabilities help you maximise the value of your existing RI portfolio and plan for renewals and new purchases.
RI Portfolio Overview
The Reserved Instances dashboard provides a comprehensive view of your RI portfolio:
Portfolio Summary
| Metric | Description |
|---|---|
| Total RIs | Number of active Reserved Instances across all services |
| Total Commitment | Annual dollar value of your RI commitments |
| Average Utilisation | Percentage of RI capacity actually being used |
| Estimated Annual Savings | Total savings achieved vs. on-demand pricing |
| Expiring Soon | RIs expiring within the next 30, 60, and 90 days |
RI Inventory
A detailed table listing every Reserved Instance in your portfolio:
| Column | Description |
|---|---|
| Service | AWS service (EC2, RDS, ElastiCache, etc.) |
| Instance Type | The reserved instance configuration |
| Region / AZ | Where the RI applies |
| Count | Number of instances reserved |
| Utilisation | Current utilisation percentage |
| Start Date | When the RI term began |
| End Date | When the RI expires |
| Payment Option | All Upfront, Partial Upfront, or No Upfront |
| Status | Active, Expired, or Payment Pending |
Utilisation Tracking
RI utilisation measures how effectively you are using the capacity you have committed to. Low utilisation means you are paying for reserved capacity that is going unused.
Understanding Utilisation
| Utilisation Level | Status | Meaning |
|---|---|---|
| 95-100% | Excellent | RI capacity is fully or nearly fully used |
| 80-94% | Good | Minor gaps, generally acceptable |
| 60-79% | Needs Attention | Significant unused capacity; investigate whether instance types or regions have changed |
| Below 60% | Poor | Substantial waste; the RI may no longer match your actual workload |
Common Causes of Low Utilisation
- Instance type mismatch -- You reserved
m5.xlargebut migrated tom6i.xlarge - Region change -- Workloads moved to a different region than the RI
- Downsizing -- Resources were rightsized to a smaller instance type
- Decommissioned workload -- The workload using the RI was retired
When utilisation drops below 80%, investigate the root cause. If the RI no longer matches your workload, consider selling it on the EC2 Reserved Instance Marketplace (for EC2 RIs) or adjust your infrastructure to use the committed capacity.
Coverage Analysis
RI coverage measures what percentage of your total usage is covered by Reserved Instances vs. on-demand pricing.
Coverage by Service
Guardian Pro breaks down coverage by AWS service to show where commitment-based discounts are being applied and where on-demand rates are still in effect:
| Service | RI Coverage | On-Demand | Potential Savings |
|---|---|---|---|
| EC2 | 75% | 25% | Covered by Savings Plans recommendation |
| RDS | 40% | 60% | RI purchase opportunity |
| ElastiCache | 0% | 100% | RI purchase opportunity |
Low coverage areas represent opportunities for additional RI purchases. However, for EC2, consider Savings Plans instead, as they offer more flexibility.
For EC2 compute, AWS now recommends Savings Plans over Reserved Instances for new commitments due to the flexibility advantages. RIs remain the primary commitment discount mechanism for RDS, ElastiCache, Redshift, OpenSearch, and other database/analytics services.
Expiry Management
One of the most valuable RI management capabilities is proactive expiry tracking. When an RI expires without renewal, the covered instances revert to on-demand pricing, often causing a noticeable cost increase.
Expiry Alerts
Guardian Pro monitors RI expiration dates and alerts you at multiple intervals:
| Alert | Timing | Purpose |
|---|---|---|
| Early Warning | 90 days before expiry | Start planning: review utilisation, assess whether to renew, modify, or let expire |
| Planning Alert | 60 days before expiry | Finalise decision: initiate procurement if renewing |
| Action Required | 30 days before expiry | Purchase renewal to avoid gap in coverage |
| Expiring This Week | 7 days before expiry | Last chance: ensure renewal is in progress |
Expiry Dashboard
The expiry view shows:
- A timeline of upcoming RI expirations
- The monthly cost impact if each RI is not renewed (the difference between the RI rate and on-demand)
- Renewal recommendations based on current utilisation
Renewal Recommendations
For each expiring RI, Guardian Pro provides a recommendation:
| Recommendation | When Suggested |
|---|---|
| Renew | Utilisation is high and the workload is expected to continue |
| Modify | Utilisation is moderate; consider changing the instance type or region to better match current usage |
| Replace with Savings Plan | For EC2 RIs, a Savings Plan may offer better flexibility |
| Let Expire | Utilisation is low or the workload is being decommissioned |
RI Recommendations for New Purchases
Beyond managing existing RIs, Guardian Pro identifies opportunities for new RI purchases based on your on-demand usage patterns:
Recommendation Details
| Field | Description |
|---|---|
| Service | The AWS service (RDS, ElastiCache, etc.) |
| Instance Type | The recommended instance configuration to reserve |
| Region | Where the RI should be purchased |
| Quantity | How many instances to reserve |
| Term | 1-year or 3-year recommendation |
| Payment Option | Recommended payment structure |
| Estimated Monthly Savings | Projected savings from the purchase |
| Break-Even Point | How long until the savings offset any upfront payment |
Purchase Considerations
Before purchasing new RIs:
- Check utilisation of existing RIs -- Ensure current RIs are well-utilised before adding more.
- Consider Savings Plans first -- For EC2, Savings Plans may be more appropriate.
- Evaluate commitment term -- 3-year terms offer deeper discounts but less flexibility. Use 1-year terms if your infrastructure is evolving.
- Rightsize first -- Implement Rightsizing recommendations before committing to avoid locking in oversized capacity.
RI Types by Service
| Service | RI Availability | Notes |
|---|---|---|
| EC2 | Standard and Convertible RIs | Consider Savings Plans instead for new purchases |
| RDS | Standard RIs | Primary discount mechanism for databases |
| ElastiCache | Standard RIs | Significant savings for production cache clusters |
| Redshift | Standard RIs | Important for sustained data warehouse usage |
| OpenSearch | Standard RIs | Available for stable OpenSearch domains |
| DynamoDB | Reserved Capacity | For predictable provisioned throughput |
Integration with Financial Advisory
The RI management view works alongside other financial features:
- Savings Plans -- Complementary discount mechanism, especially for EC2
- Savings Tracker -- Track realised savings from RI investments
- Rightsizing -- Ensure resources are optimally sized before committing
Notifications
Configure RI-related notifications in Settings > Notifications:
- Expiry alerts -- Email and in-app alerts at configurable intervals before RI expiration
- Utilisation alerts -- Notifications when RI utilisation drops below a threshold
- Coverage reports -- Periodic summaries of RI coverage across your portfolio
Best Practices
Maintain a Renewal Calendar
Even with automated alerts, maintain a team calendar with RI renewal dates. Assign an owner for each renewal decision to ensure nothing falls through the cracks.
Balance Flexibility and Savings
- Use Convertible RIs when you expect to change instance types during the term
- Use Standard RIs when your workload is stable and predictable
- Consider a mix of 1-year and 3-year terms to stagger renewals
Monitor Monthly
Review RI utilisation and coverage monthly as part of your cost governance process. Changes in your infrastructure can quickly render an RI underutilised.
Next Steps
- Savings Plans -- Explore Savings Plans as a flexible alternative to EC2 RIs
- Savings Tracker -- Track savings from your RI portfolio
- Cost Dashboard -- Return to the cost overview