Reference >
Atlas M0 (Free Tier), M2, and M5 Limitations

Atlas M0 (Free Tier), M2, and M5 Limitations¶

Configuration Limitations¶

The following table lists the configuration limitations of Atlas M0 Free Tier and M2/M5 shared clusters:

Configuration Option	Limitation
Cloud Service Provider and Region	`M0` Free Tier clusters and `M2/M5` shared clusters are only deployable in a subset of regions on AWS, GCP, and Azure. For more information on which cloud provider regions support free and shared tiers, see: Amazon Web Services (AWS) Google Cloud Platform (GCP) Microsoft Azure
MongoDB Version and Storage Engine	Atlas locks the MongoDB version and storage engine for `M0/M2/M5` clusters to MongoDB 4.2 with WiredTiger. MongoDB 4.4 on Shared Tier Clusters You can deploy MongoDB 4.4 in Atlas free and shared-tier clusters (`M0`, `M2` and `M5`) only in AWS region `us-east-1`.
MongoDB Version Upgrade	You can’t upgrade the MongoDB version that `M0/M2/M5` clusters run. Atlas upgrades `M0/M2/M5` clusters to the newest MongoDB version after several patch versions become available for that version. To learn more about how MongoDB versions its software, see MongoDB Versioning.
Cluster Tier	You must select the `M0` cluster tier to deploy a Free Tier cluster.
Cluster Memory	You cannot configure memory for `M0` Free Tier or `M2/M5` shared clusters.
Cluster Storage	You cannot configure storage size for `M0` Free Tier or `M2/M5` shared clusters.
Replication Factor	Replication Factor is set to `3 Nodes` and cannot be modified for `M0` Free Tier, or `M2/M5` shared clusters.
Replica Set Tags	`M0` Free Tier, and `M2/M5` shared clusters are not configured with pre-defined replica set tags.
Do You Want A Sharded Cluster	You cannot deploy a `M0` Free Tier or `M2/M5` shared cluster as a Sharded Cluster.
Do You Want To Enable Backup	You cannot enable backups on `M0` Free Tier clusters. Backup Alternative: mongodump You may use mongodump to back up your data and mongorestore to restore that data. To learn how to manually back up your data, see Command Line Tools.
Test Failovers	You cannot perform primary failover testing on `M0` Free Tier or `M2/M5` shared clusters.
Database Auditing	You cannot configure database auditing on `M0` Free Tier or `M2/M5` shared clusters.
Encryption at Rest using your Key Management	You cannot configure Encryption at Rest using Customer Key Management on `M0` Free Tier or `M2/M5` shared clusters.
Network Peering Connections	You cannot configure Set up a Network Peering Connection on `M0` Free Tier or `M2/M5` shared clusters.
Access Tracking	You cannot view the database access history for `M0` Free Tier, or `M2/M5` shared clusters.

Operational Limitations¶

The following table lists the operational limitations of Atlas M0 Free Tier and M2/M5 shared clusters:

Configuration Option	Limitation
Aggregation	Atlas `M0` Free Tier clusters do not support the `allowDiskUse` option for the aggregation command or its helper method. On Free Tier and shared clusters, aggregation fields that represent database and collection names (such as $merge into and $out values) cannot accept expressions as values.
Throughput	Maximum operations: `M0`: 100 per second `M2`: 200 per second `M5`: 500 per second
Sort in Memory	`M0/M2/M5` sort in memory limit is 32 MB.
Query Utilization	The percentage of time that a query is running over any five minute period must remain under 100% on `M0` Free Tier and `M2/M5` shared clusters.
Connections	`M0` Free Tier and `M2/M5` shared clusters are allowed a maximum of 500 connections.
Data Transfer Limits	`M0/M2/M5` clusters limit the total data transferred into or out of the cluster in a rolling seven-day period. This varies by cluster tier as follows: `M0`: 10 GB in and 10 GB out per period `M2`: 20 GB in and 20 GB out per period `M5`: 50 GB in and 50 GB out per period Atlas throttles the network speed of clusters which exceed the posted limits.
JavaScript	`M0` Free Tier and `M2/M5` shared clusters do not support server-side JavaScript. Example $where and map-reduce are not supported.
API Access	You cannot modify or configure an `M0` Free Tier cluster using the Clusters API endpoint. A subset of API endpoints support `M2` and `M5` shared clusters.
Number of Free Tier clusters	You can deploy at most one `M0` Free Tier cluster per Atlas project.
Database Commands	Certain database commands are unsupported or behavior differently in an `M0` Free Tier cluster. To learn more, see Command Limitations in Free Tier Clusters. Please contact Atlas support for any questions or comments related to restricted commands.
Atlas Monitoring	The Metrics view of an `M0` Free Tier or `M2/M5` shared cluster only displays the following metrics: Connections Logical Size Network Opscounter For more information on these metrics, see Real Time Metrics.
Atlas Alerts	`M0/M2/M5` clusters can only trigger alerts configured with one of the following alert conditions: Connections Logical Size Network Opscounter
Namespaces and Database Names	`M0` Free Tier and `M2/M5` shared cluster namespaces are limited to 95 bytes. Database names are limited to 38 bytes.
Database and Collections	`M0` Free Tier and `M2/M5` shared clusters have a maximum of 100 databases and 500 collections total.
Database Logs	`M0` Free Tier and `M2/M5` shared clusters do not provide downloadable logs.
Cluster Persistance	Atlas may deactivate idle `M0` Free Tier clusters as per the Terms of Service.
Auto-Expand Storage	`M0` Free Tier and `M2/M5` shared clusters do not provide automatically scaling storage.
Performance Advisor	`M0` Free Tier and `M2/M5` shared clusters do not provide access to the Performance Advisor.
Real-Time Performance Panel	`M0` Free Tier and `M2/M5` shared clusters do not provide access to the Real-Time Performance Panel.
Build Index with Rolling Build	`M0` Free Tier and `M2/M5` shared clusters do not provide the ability to build indexes with a rolling build.
Custom Roles	Changes to custom roles make take up to 30 seconds to deploy in `M0` Free Tier and `M2/M5` shared clusters.

← Atlas Limitations Unsupported Commands in Atlas →