# Missing Reserved Capacity for Steady Cosmos DB Throughput Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/missing-reserved-capacity-for-steady-cosmos-db-throughput Production Cosmos DB accounts usually carry a stable floor of provisioned throughput that runs every hour of the year: core containers on manual RU/s,... By: PointFive Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) The short version Production Cosmos DB accounts usually carry a stable floor of provisioned throughput that runs every hour of the year: core containers on manual RU/s, the 10% minimum of autoscale containers, and the same throughput repeated in every replica region. PointFive Research Cloud cost research at PointFive Azure service [Azure Cosmos DB](https://www.pointfive.co/efficiency-hub/cloud-services/azure-cosmos-db) Category [Databases](https://www.pointfive.co/efficiency-hub/service-category/databases) Reference CER-0440 Type Suboptimal Pricing Model ## Explanation Why the waste happens and who it affects. That floor is billed at pay-as-you-go rates unless it is covered by Cosmos DB reserved capacity, which discounts provisioned RU/s for a one- or three-year commitment and applies automatically to matching resources. Cosmos DB is often left out of commitment reviews that focus on VMs, and sizing is harder than for compute: reservations are bought in RU/s, autoscale throughput in single-write-region accounts consumes reservations at 1.5 times its RU/s, and some regions consume reservations at a higher ratio. Azure Advisor raises a dedicated purchase recommendation for Cosmos DB reservations, and Microsoft states discounts of up to 63% compared with regular prices. ## Billing model The pricing dimensions that drive this cost. Pay-as-you-go throughput Provisioned RU/s billed per hour at standard, autoscale or multi-region write rates, per region Fixed-discount reservation Multiples of 100 RU/s for 1 or 3 years, at 20% (1 year) or 30% (3 years) off regular prices Progressive reservation Units from 1,000,000 RU/s upward with larger discounts, up to 63% for the biggest three-year multi-region write units Reservation consumption Hourly and use-it-or-lose-it; autoscale RU/s in single write region accounts count 1.5 times, multiplied by the regional ratio ## How to detect 4 checks to find it in your estate. - Review Azure Advisor for 'Consider Cosmos DB reserved instance to save over the pay-as-you-go costs' and the Recommended tab when purchasing an Azure Cosmos DB reservation, which analyzes the last 7, 30 and 60 days of hourly usage - Chart the Provisioned Throughput metric summed across accounts and regions in the intended scope over 30 to 60 days and take the lowest sustained hourly value as the reservable baseline - In Cost analysis, filter to Azure Cosmos DB and group by meter and pricing model to see how much provisioned throughput is billed at pay-as-you-go rates rather than covered by a reservation or savings plan - Exclude serverless accounts, storage and network charges from the analysis, since reservations don't cover them ## How to fix 5 ways to remove the waste. - Buy reserved capacity for the steady baseline only, summing RU/s across all regions of each account and applying the 1.5 multiplier for single-write-region autoscale throughput and the regional ratios where they apply - Choose the throughput type that matches the accounts (100 RU/s or 100 multi-region write RU/s units), and use the largest progressive unit that fits for estates of 1,000,000 RU/s or more - Use shared or management group scope so the reservation follows throughput across subscriptions, and use exchanges when the baseline changes - Consider the savings plan for databases, which covers Azure Cosmos DB with an hourly spend commitment, where throughput is spread across services or likely to shift - Rightsize idle containers and fix throughput mode first, so the reservation isn't sized to waste ## Documentation Vendor references for pricing and configuration. - [Pricing & Discounts With Reserved Capacity - Azure Cosmos DB learn.microsoft.com](https://learn.microsoft.com/en-us/azure/cosmos-db/reserved-capacity) - [Cost recommendations - Azure Advisor learn.microsoft.com](https://learn.microsoft.com/en-us/azure/advisor/advisor-reference-cost-recommendations) - [What are savings plans? learn.microsoft.com](https://learn.microsoft.com/en-us/azure/cost-management-billing/savings-plan/savings-plan-overview) - [Optimize Cost for Multi-Region Deployments - Azure Cosmos DB learn.microsoft.com](https://learn.microsoft.com/en-us/azure/cosmos-db/optimize-cost-regions) - [Azure Cosmos DB pricing azure.microsoft.com](https://azure.microsoft.com/en-us/pricing/details/cosmos-db/autoscale-provisioned/) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - Azure Cosmos DB CER-0439 ### [Mismatched Throughput Mode on Cosmos DB Containers](https://www.pointfive.co/efficiency-hub/inefficiencies/mismatched-throughput-mode-on-cosmos-db-containers) Cosmos DB provisioned throughput comes in two modes. Standard (manual) throughput bills the RU/s you set every hour regardless of use. Autoscale lets the system scale between 10% and 100% of a maximum (Tmax) and bills the highest RU/s... Databases - Azure Cosmos DB CER-0142 ### [Infrequently Accessed Data Stored in Azure Cosmos DB](https://www.pointfive.co/efficiency-hub/inefficiencies/infrequently-accessed-data-stored-in-azure-cosmos-db) Azure Cosmos DB is optimized for low-latency, globally distributed workloads - not long-term storage of infrequently accessed data. Yet in many environments, cold data such as logs, telemetry, or historical records is retained in Cosmos DB... Databases - Azure Cosmos DB CER-0438 ### [Idle Cosmos DB Containers with Provisioned Throughput](https://www.pointfive.co/efficiency-hub/inefficiencies/idle-cosmos-db-containers-with-provisioned-throughput) Containers and databases created for load tests, migrations, retired features, proofs of concept or one-off data loads often keep their provisioned throughput long after traffic stops. Provisioned RU/s is reserved capacity: it is billed... Databases --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.