# Inactive DocumentDB Cluster | Cloud Efficiency Hub Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/inactive-documentdb-cluster Amazon DocumentDB instance-based clusters bill every instance for each second it runs, whether or not any client is connected, and storage, I/O and... By: PointFive Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) The short version Amazon DocumentDB instance-based clusters bill every instance for each second it runs, whether or not any client is connected, and storage, I/O and backup storage are billed on top. PointFive Research Cloud cost research at PointFive AWS service [AWS DocumentDB](https://www.pointfive.co/efficiency-hub/cloud-services/aws-documentdb) Category [Databases](https://www.pointfive.co/efficiency-hub/service-category/databases) Reference CER-0375 Type Idle or Unused Resource ## Explanation Why the waste happens and who it affects. Clusters created to evaluate DocumentDB, to rehearse a MongoDB migration, or for services that were later retired are frequently left running with a primary and one or more replicas and no connections at all. DocumentDB Serverless clusters also keep billing capacity while idle, because capacity does not scale below the configured minimum. Stopping is only a partial answer: a stopped DocumentDB cluster stops instance charges but still bills storage, manual snapshots and automated backup storage, and DocumentDB automatically starts it again after seven days, at which point instance charges resume. AWS Compute Optimizer produces idle recommendations for DocumentDB clusters that have had no database connections over its lookback period. ## Billing model The pricing dimensions that drive this cost. Instance hours Each instance is billed per second with a 10-minute minimum, from launch until it is stopped or deleted Cluster storage and I/O Storage billed per GB-month, plus I/O billed per million requests on the Standard storage configuration Backup storage Free up to 100 percent of the cluster's data storage, then billed per GB-month; manual snapshots persist after deletion Serverless capacity DocumentDB Serverless bills DocumentDB Capacity Units per second for capacity used, never below the configured minimum Stopped cluster No instance charges, but storage, manual snapshots and backup storage continue, and the cluster restarts after seven days ## How to detect 4 checks to find it in your estate. - Review AWS Compute Optimizer idle recommendations for Amazon DocumentDB, which flag provisioned and serverless clusters in available status with no database connections over the 14-day default lookback (elastic clusters are excluded) - Check the DatabaseConnections CloudWatch metric (AWS/DocDB namespace, customer-initiated connections only) for every instance over 14 to 30 days, together with DocumentsReturned, DocumentsInserted, DocumentsUpdated and DocumentsDeleted; opcounter metrics are not a reliable idle signal because AWS notes they stay around 50 on idle clusters due to internal health checks - Look for clusters that are repeatedly stopped and automatically restarted after seven days, which indicates a cluster kept only in case it is needed - Confirm with owners, tags and application configuration that no service, migration job or DMS task still points at the cluster endpoint ## How to fix 4 ways to remove the waste. - Take a final snapshot and delete the cluster and its instances when it is no longer needed (a stopped cluster must be started first, because it cannot be deleted while it still has instances); the snapshot can be restored later and bills only for backup storage - Delete read replicas that receive no reads before deciding on the cluster as a whole - For clusters needed only occasionally, stop them between uses and automate the stop again after the seven-day automatic restart, or move them to DocumentDB Serverless with a low minimum capacity - Review and expire manual snapshots left behind after deletion so they do not accumulate backup storage charges ## Documentation Vendor references for pricing and configuration. - [Amazon DocumentDB Pricing aws.amazon.com](https://aws.amazon.com/documentdb/pricing/) - [Stopping and starting an Amazon DocumentDB cluster docs.aws.amazon.com](https://docs.aws.amazon.com/documentdb/latest/developerguide/db-cluster-stop-start.html) - [Viewing idle resource recommendations docs.aws.amazon.com](https://docs.aws.amazon.com/compute-optimizer/latest/ug/view-idle-recommendations.html) - [Monitoring Amazon DocumentDB with CloudWatch docs.aws.amazon.com](https://docs.aws.amazon.com/documentdb/latest/developerguide/cloud_watch.html) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - AWS DocumentDB CER-0376 ### [Suboptimal Storage Configuration for DocumentDB Cluster](https://www.pointfive.co/efficiency-hub/inefficiencies/suboptimal-storage-configuration-for-documentdb-cluster) Starting with Amazon DocumentDB 5.0, instance-based clusters can use one of two storage configurations. Standard storage bills I/O on a pay-per-request basis on top of instance and storage charges, while I/O-optimized storage removes I/O... Databases - AWS RDS CER-0299 ### [Orphaned RDS Backup Storage After Database Deletion](https://www.pointfive.co/efficiency-hub/inefficiencies/orphaned-rds-backup-storage-after-database-deletion) An RDS database instance is deleted but its manual snapshots or retained backups remain. Unlike automated backups tied to a live instance, these backups persist independently and continue generating storage costs despite no longer... Databases - AWS Aurora CER-0293 ### [Automatic Restart of Stopped Aurora Clusters Causing Unintended Compute Charges](https://www.pointfive.co/efficiency-hub/inefficiencies/automatic-restart-of-stopped-aurora-clusters-causing-unintended-compute-charges) Amazon Aurora database clusters are intentionally stopped to avoid compute costs but are automatically restarted by the service after the maximum allowed stop period. Once restarted, re-started database instances begin accruing... Databases --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.