The cluster tier dictates the memory, storage, and IOPS specification for each data-bearing server  in the cluster.
You might see different values depending on your selected cloud provider and region.
Shared clusters are economical clusters for getting started with MongoDB and for low-throughput applications. These clusters deploy to a shared environment with access to a subset of Atlas features and functionality. For complete documentation on shared cluster limits and restrictions, see Atlas M0 (Free Tier), M2, and M5 Limitations.
M0 clusters are free sandbox replica set clusters. You can deploy
M0 cluster per Atlas project. You can
M0 Free Tier cluster to an
M2+ paid cluster at any time.
M5 clusters are low-cost shared starter clusters.
These clusters provide the following additional features and
functionality compared to
Atlas deploys MongoDB 4.2 for all Shared Clusters (
M5). However, Shared Clusters Clusters do not support all functionality in MongoDB version 4.2 and later. See Atlas M0 (Free Tier), M2, and M5 Limitations for details.NoteMongoDB 4.4 on Shared Tier Clusters
You can deploy MongoDB 4.4 in Atlas free and shared-tier clusters (
M5) only in AWS region
Atlas supports shared cluster deployment in a subset of Cloud Providers and Regions. Atlas greys out any shared cluster tiers not supported by the selected cloud service provider and region. For a complete list of regions that support shared cluster deployments, see:
Dedicated Clusters for Low-Traffic Applications¶
These cluster tiers support development environments and low-traffic applications.
These clusters support replica set deployments only, but otherwise provide full access to Atlas features and functionality.
M20 clusters for
- Development environments
- Low-traffic production use
M20 clusters hosted on AWS experience periods
of high usage, they can temporarily increase performance through
During periods of low usage,
M20 clusters accumulate
EC2 instance credits,
and these credits are depleted when bursting occurs. The
System: CPU (Steal) % is alert is triggered when the EC2 instance credit balance is
Dedicated Clusters for High-Traffic Applications¶
M30 and higher cluster tiers support production environments with
high traffic applications and large datasets.
These clusters support replica set and sharded cluster deployments with full access to Atlas features and functionality.
Some clusters have variants, denoted by the ❯ character. When you select these clusters, Atlas lists the variants and tags each cluster to distinguish their key characteristics.
NVMe Storage on AWS Clusters¶
For applications hosted on AWS which require low-latency and high-throughput I/O, Atlas offers storage options using locally attached ephemeral NVMe SSD