# Cold Data Kept on MongoDB Atlas Cluster Storage Instead of Online Archive Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/cold-data-kept-on-mongodb-atlas-cluster-storage-instead-of-online-archive Event, log, audit, order-history and time-series collections in MongoDB tend to grow without limit, while applications query only recent documents. By: PointFive Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) The short version Event, log, audit, order-history and time-series collections in MongoDB tend to grow without limit, while applications query only recent documents. PointFive Research Cloud cost research at PointFive MongoDB Atlas service [MongoDB Atlas](https://www.pointfive.co/efficiency-hub/cloud-services/mongodb-atlas) Category [Storage](https://www.pointfive.co/efficiency-hub/service-category/storage) Reference CER-0536 Type Excessive Data Retention ## Explanation Why the waste happens and who it affects. When older documents stay on the cluster, they occupy disk on every data-bearing node, enlarge every backup snapshot, and add to the working set and indexes the tier must support. Because custom storage is billed for the full configured amount and storage auto-scaling only grows disks, retained history steadily raises storage and backup cost and can push the cluster to a larger tier. MongoDB's billing optimization guidance recommends using Online Archive or TTL indexes to move older data from more expensive hot storage to less expensive cold storage. Online Archive, available on M10 and larger clusters, moves documents matching a date-based or custom rule to Atlas-managed cloud object storage, where they remain queryable read-only through Atlas Data Federation. TTL indexes delete documents automatically after a set age where the data does not need to be kept at all. ## Billing model The pricing dimensions that drive this cost. Cluster storage Default storage is included in the tier's hourly rate; custom storage is billed for the full configured amount Backup storage Snapshot storage is billed per GB-month, so data kept on the cluster is also carried in retained snapshots Online Archive storage Archived data is billed by GB stored and days retained, at rates that vary by cloud provider and region Online Archive queries $5.00 per TB of archived data processed, with a 10 MB minimum per query, plus data transferred and returned ## How to detect 4 checks to find it in your estate. - Identify the largest collections by storage size and index size in Data Explorer or with db.collection.stats(), and check whether they hold time-stamped documents far older than the application's access window - Use the Query Profiler or Performance Advisor to confirm that queries on those collections filter on recent date ranges and rarely touch older documents - Flag collections with no TTL index (check db.collection.getIndexes() for expireAfterSeconds) and no Online Archive rule on the cluster's Online Archive tab - Estimate the storage, backup and tier impact of the cold portion by comparing document counts or sizes by date range, and check whether storage auto-scaling events coincide with the growth ## How to fix 5 ways to remove the waste. - Configure Online Archive on M10+ clusters with a date-based rule (date field plus days to keep on the cluster) or a custom query, and index the date field, which MongoDB recommends for archiving performance - Query archived data through the federated connection string that Atlas creates, and use query limits and explain() to control the per-TB processing charges if archived data is still read - Set a Data Retention Period on the archive where regulations allow, so Atlas deletes archived data after 7 to 9125 days; deleted archive data cannot be recovered - Use TTL indexes (expireAfterSeconds on a date field) for data that can simply expire, such as sessions, logs and ephemeral events - After archiving or expiring large volumes, reduce the cluster's configured storage and revisit the tier, since freed space does not shrink the disk automatically ## Documentation Vendor references for pricing and configuration. - [Billing Breakdown and Optimization mongodb.com](https://www.mongodb.com/docs/atlas/billing/billing-breakdown-optimization/) - [Online Archive Overview mongodb.com](https://www.mongodb.com/docs/atlas/online-archive/overview/) - [Online Archive Costs mongodb.com](https://www.mongodb.com/docs/atlas/billing/online-archive/) - [Configure Online Archive for Standard Collections mongodb.com](https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-standard/) - [TTL Indexes mongodb.com](https://www.mongodb.com/docs/manual/core/index-ttl/) - [Cluster Configuration Costs mongodb.com](https://www.mongodb.com/docs/atlas/billing/cluster-configuration-costs/) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - MongoDB Atlas CER-0533 ### [Excessive Snapshot Retention and Cross-Region Copies in MongoDB Atlas Cloud Backup](https://www.pointfive.co/efficiency-hub/inefficiencies/excessive-snapshot-retention-and-cross-region-copies-in-mongodb-atlas-cloud-backup) Atlas Cloud Backup takes scheduled snapshots of dedicated clusters and bills the retained snapshot storage per GB-month. The default backup policy is generous: snapshots every 6 hours (every 12 on NVMe clusters) kept for 7 days, daily... Storage - MongoDB Atlas CER-0535 ### [Overprovisioned MongoDB Atlas Storage After Auto-Scaling](https://www.pointfive.co/efficiency-hub/inefficiencies/overprovisioned-mongodb-atlas-storage-after-auto-scaling) Atlas storage auto-scaling, enabled by default for new clusters, increases a cluster's disk when used space reaches 90% on any node, and it scales storage up only. When a cluster grows past its tier's default storage, Atlas bills the full... Storage - MongoDB Atlas CER-0326 ### [Continuous Backup Enabled on Non-Production MongoDB Atlas Clusters](https://www.pointfive.co/efficiency-hub/inefficiencies/continuous-backup-enabled-on-non-production-mongodb-atlas-clusters) MongoDB Atlas offers two backup mechanisms for dedicated clusters: Cloud Backups (scheduled snapshots using the underlying cloud provider's native snapshot functionality) and Continuous Cloud Backup, which adds point-in-time recovery by... Databases --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.