Docs Menu

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

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

Configuration Option
Limitation
Cloud Service Provider and Region

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:

MongoDB Version and Storage Engine
Atlas uses MongoDB 4.4 for M0/M2/M5 clusters.
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 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 cluster.
Cluster Memory
You can't configure memory for M0 free clusters or M2/M5 shared clusters.
Cluster Storage
You can't configure storage size for M0 free clusters or M2/M5 shared clusters.
Replication Factor
Replication Factor is set to 3 Nodes and you can't modify it for M0 free clusters or M2/M5 shared clusters.
Replica Set Tags
M0 free clusters and M2/M5 shared clusters do not have pre-defined replica set tags.
Do You Want A Sharded Cluster
You can't deploy a M0 free cluster or M2/M5 shared cluster as a Sharded Cluster.
Do You Want To Enable Backup

You can't enable backups on M0 free clusters.

Tip
See also:

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 can't perform primary failover testing on M0 free clusters or M2/M5 shared clusters.
Database Auditing
You can't configure database auditing on M0 free clusters or M2/M5 shared clusters.
Encryption at Rest using your Key Management
You can't configure encryption at Rest using Customer Key Management on M0 free clusters or M2/M5 shared clusters.
Network Peering Connections
You can't configure network peering connections on M0 free clusters or M2/M5 shared clusters.
Access Tracking
You can't view the database access history for M0 free clusters or M2/M5 shared clusters.
Configure TLS Certificate Root
You can't modify the Certificate Authority that MongoDB Atlas clusters use through the API for M0 free clusters and M2/M5 shared clusters.

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

Operation
Limitation

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.

API Access

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.

Note

You can create an M0 free cluster using the Clusters API resource. You can create only one M0 free cluster per project.

Atlas Alerts

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
Atlas Monitoring

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.

Authentication

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

  • Password (SCRAM-SHA1)
  • X.509 Certificates
  • AWS IAM
Auto-Expand Storage
M0 free clusters and M2/M5 shared clusters do not provide automatically scaling storage.
BSON Nested Object Depth
M0 free clusters and M2/M5 shared clusters can store documents with a maximum of 50 nested levels.
Build Index with Rolling Build
M0 free clusters and M2/M5 shared clusters do not provide the ability to build indexes with a rolling build.
Cluster Persistence
Atlas may deactivate idle M0 free clusters as per the Terms of Service.
Connections
M0 free clusters and M2/M5 shared clusters can only have a maximum of 500 connections.
Cursors
Free clusters and shared clusters can't use the
noTimeout cursor option.
Custom Roles
Changes to custom roles might take up to 30 seconds to deploy in M0 free clusters and M2/M5 shared clusters.
Database and Collections
M0 free clusters and M2/M5 shared clusters can have a maximum of 100 databases and 500 collections total.
Database Commands

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.

Database Logs
M0 free clusters and M2/M5 shared clusters do not provide downloadable logs.
Data Recovery
  • 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.
Data Transfer Limits

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.
JavaScript

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

Example

$where and map-reduce are not supported.

Namespaces and Database Names
M0 free cluster and M2/M5 shared cluster namespaces are limited to 95 bytes. Database names are limited to 38 bytes.
Number of Free Clusters
You can deploy at most one M0 free cluster per Atlas project.
Performance Advisor
M0 free clusters and M2/M5 shared clusters do not provide access to the Performance Advisor.
Query Utilization
The percentage of time that a query is running over any five minute period must remain under 100% on M0 free clusters and M2/M5 shared clusters.
Real-Time Performance Panel
M0 free clusters and M2/M5 shared clusters do not provide access to the Real-Time Performance Panel.
Sort in Memory
M0 free clusters and M2/M5 shared clusters sort in memory limit is 32 MB.
Throughput

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.
Automatic Pause of Idle Clusters
Atlas automatically pauses M0 free clusters after 60 days of inactivity where there are zero connections to the cluster. You can resume the cluster at any time.
Driver
Description
Drivers that use a JRE or JDK'

Due to an issue with TLS 1.3 support in the Java JDK' (JDK-8236039), upgrade the JDK' that supports the driver you use to connect to Atlas.

Minimum versions of the JDK' include:

14u-cpu
14.0.2
13.0.3
11.0.8-oracle
11.0.7
8u261
emb-8u261

To learn more about support for TLS 1.3 in Java-based languages, libraries, and drivers, see:

Give Feedback
© 2021 MongoDB, Inc.

About

  • Careers
  • Legal Notices
  • Privacy Notices
  • Security Information
  • Trust Center
© 2021 MongoDB, Inc.