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

You can only deploy M0 free clusters and M2/M5 shared clusters in a subset of regions on AWS, GCP, and Azure. To learn more about supported cloud provider regions for free clusters and shared clusters, see:

• Amazon Web Services (AWS)
• Google Cloud Platform (GCP)
• Microsoft Azure

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 that version. To learn more about how MongoDB versions its software, see MongoDB Versioning.

You can't enable backups on M0 free clusters.

Atlas M0 free clusters and M2/M5 shared clusters do not support the allowDiskUse option for the aggregation command or its helper method.

On M0 free clusters and M2/M5 shared clusters, aggregation fields that represent database and collection names, such as $merge and $out values, can't accept expressions. as values. On M0 free clusters and M2/M5 shared clusters, aggregation pipelines can have a maximum of 50 stages.

While you can create an M0 free cluster using the Clusters API resource, you cannot modify an M0 free cluster using the Clusters API resource. A subset of API endpoints support M2 and M5 shared clusters.

M0 free clusters and M2/M5 shared clusters clusters can only trigger alerts configured with one of the following alert conditions:

• Connections
• Logical Size
• Network
• Opscounter

The Metrics view of an M0 free cluster or M2/M5 shared cluster only displays the following metrics:

• Connections
• Logical Size
• Network
• Opscounter

To learn more, see Real Time Metrics.

M0 free clusters and M2/M5 shared clusters support only the following authentication methods:

• Password (SCRAM-SHA1)
• X.509 Certificates
• AWS IAM

Free clusters and shared clusters can't use the

noTimeout cursor option.

Certain database commands are unsupported or behave differently in an M0 free cluster. To learn more, see Command Limitations in Free Clusters.

Please contact Atlas support for any questions or comments related to restricted commands.

• Custom policies are not supported for M2 and M5 cluster snapshots. Atlas always takes a single daily snapshot at the same time, starting 24 hours after the cluster was created.

  If you require finer-grained backups, consider upgrading to an M10 or larger cluster tier.

• On-demand snapshots are not supported for M2 and M5 clusters.
• You can't restore M2 and M5 snapshots to a sharded cluster. You can only restore M2 and M5 snapshots to replica sets.
• You can't restore serverless instance snapshots to M2 and M5 clusters.

M0 free clusters and M2/M5 shared clusters limit the total data transferred into or out of the cluster in a rolling seven-day period. The rate limits vary 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 handles clusters that exceed the rate limit as follows:

• Atlas throttles the network speed of the cluster.
• Atlas triggers a one second cooldown period before resuming the cluster's operations on a given connection. If the queue is greater than the operations per second limit, operations might wait for more than a second in the queue.
• If the amount of transferred data drops below the rate limit threshold, Atlas resumes processing of the queued data transfers on each connection before processing any new data transfers on that connection.

M0 free clusters and M2/M5 shared clusters do not support server-side JavaScript.

M0 free clusters allow up to 100 operations per second.

Atlas handles clusters that exceed the operations per second rate limit as follows:

• Atlas throttles the network speed of the cluster.
• Atlas triggers a one second cooldown period before resuming the cluster's operations on a given connection. If the queue is greater than the operations per second limit, operations might wait for more than a second in the queue.
• If the number of operations per second drops below the rate limit threshold, Atlas resumes processing of the queued operations on each connection before processing any new operations on that connection.