Low Commitment Coverage for Steady-State OpenSearch Service Domains

When none of that usage is covered by a commitment, every instance-hour is billed at the On-Demand rate even though the baseline is predictable. OpenSearch Service offers two ways to discount it: Reserved Instances for a specific instance type in a Region, and Database Savings Plans, a dollar-per-hour commitment that also covers OpenSearch Serverless.

Coverage gaps are common because OpenSearch spend is often owned by a platform or observability team rather than the group that manages EC2 commitments, because OpenSearch Reserved Instances are not size flexible and teams hesitate to lock in an instance type, and because reservations expire silently and usage returns to On-Demand. Database Savings Plans added OpenSearch Service only in March 2026, so commitment strategies written earlier may not consider it.

Managed domains are billed per instance-hour at On-Demand rates unless a commitment applies.

On-Demand instance-hours

Billed for each hour a node runs in an available state, at the full published rate for its instance type

Reserved Instances

1- or 3-year terms with No, Partial or All Upfront payment, applied only to the exact instance type reserved, and charged for the full term even if no matching instance runs

Database Savings Plans

A 1-year, no upfront commitment in dollars per hour that applies to eligible OpenSearch managed cluster and Serverless usage regardless of instance family, size or Region, covering Generation 7 and newer instances

No stacking

Database Savings Plans cannot be combined with Reserved Instances on the same workload

• Review the Trusted Advisor check Amazon OpenSearch Service Reserved Instance purchase recommendations, sourced from Cost Optimization Hub, which flags accounts with an identified OpenSearch savings action
• Open Cost Explorer reservation recommendations with OpenSearch Service selected, using a 30- or 60-day lookback, and compare the recommended instance counts with the domains that have run unchanged over that period
• Group OpenSearch Service spend by Purchase Option in Cost Explorer to see what share of instance-hours is billed On-Demand
• Review Database Savings Plans purchase recommendations and coverage, noting that only Generation 7 and newer instance types are eligible, so domains on older families will not be covered until they are upgraded
• List existing OpenSearch Reserved Instances and their end dates to catch reservations that are about to expire

• Cover domains whose instance type and count are unlikely to change for the term with Reserved Instances; because they apply only to the exact instance type, align them with any planned instance migration first
• Use Database Savings Plans for OpenSearch baselines that may change instance family, size or Region, move to Serverless, or shift between database services, accepting a lower maximum discount in exchange for that flexibility
• Do not plan to cover the same workload with both; assign each baseline to one commitment type
• Right-size and move domains to current-generation instances before committing, so the commitment is sized to the capacity the domain actually needs and, for Savings Plans, the instances are eligible
• Size commitments to the minimum steady usage and review coverage and upcoming expirations on a regular schedule so usage does not silently return to On-Demand

• Amazon OpenSearch Service Pricingaws.amazon.com
• Reserved Instances in Amazon OpenSearch Servicedocs.aws.amazon.com
• Cost optimization techniques for Amazon OpenSearch Servicedocs.aws.amazon.com
• Database Savings Plansaws.amazon.com
• Accessing reservation recommendationsdocs.aws.amazon.com
• Cost optimization - AWS Supportdocs.aws.amazon.com