> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

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# Manage Clusters

Use the following resources to configure and manage Atlas clusters.

For general guidance on MongoDB version numbering, release types, and upgrade paths, see [MongoDB Versions and Upgrade Paths.](https://www.mongodb.com/docs/mongodb-versions.md#std-label-versions-and-upgrade-paths)

## View Your Clusters

### Required Access

To view your clusters, you must have [`Project Read Only`](https://www.mongodb.com/docs/atlas/reference/user-roles.md#mongodb-authrole-Project-Read-Only) access or higher to the project.

### Procedure

### Atlas CLI

To list all clusters for your project using the Atlas CLI, run the following command:

```sh

atlas clusters list [options]

```

To return the details for the cluster you specify using the Atlas CLI, run the following command:

```sh

atlas clusters describe <clusterName> [options]

```

To learn more about the syntax and parameters for the previous commands, see the Atlas CLI documentation for [atlas clusters list](https://www.mongodb.com/docs/atlas/cli/current/command/atlas-clusters-list/) and [atlas clusters describe.](https://www.mongodb.com/docs/atlas/cli/current/command/atlas-clusters-describe/)

**See also: Related Links**

- [Install the Atlas CLI](https://www.mongodb.com/docs/atlas/cli/current/install-atlas-cli/)

- [Connect to the Atlas CLI](https://www.mongodb.com/docs/atlas/cli/current/connect-atlas-cli/)

To return the advanced configuration settings details for the cluster you specify using the Atlas CLI, run the following command:

```sh

atlas clusters advancedSettings describe <clusterName> [options]

```

To learn more about the command syntax and parameters, see the Atlas CLI documentation for [atlas clusters advancedSettings describe.](https://www.mongodb.com/docs/atlas/cli/current/command/atlas-clusters-advancedSettings-describe/)

## Cluster Tiers

You can select a cluster tier when you [create a new cluster](https://www.mongodb.com/docs/atlas/manage-clusters.md#std-label-create-cluster-instance) or [modify an existing cluster.](https://www.mongodb.com/docs/atlas/manage-clusters.md#std-label-create-cluster-instance)

On Atlas Core clusters, the cluster tier sets the RAM, vCPUs, and storage for each data-bearing server  in the cluster. On Atlas Infinite clusters, the cluster tier sets the RAM, vCPUs, and IOPS (Input/Output Operations per Second) for each node in the cluster.

On Atlas Infinite clusters, the cluster tier also fixes the storage IOPS (Input/Output Operations per Second) and storage throughput values. These values don't change as the amount of data you store grows. To review the storage performance for each tier, see [Atlas Infinite Storage IOPs and Throughput Values per Cluster Tier.](https://www.mongodb.com/docs/atlas/reference/amazon-aws.md#std-label-atlas-infinite-storage-iops-throughput-values)

On Atlas Core clusters, data-bearing servers are the machines that run the nodes holding your application data. In a sharded cluster, each shard is a replica set whose members are the data-bearing servers. Sharded clusters may also use [config servers](https://www.mongodb.com/docs/manual/core/sharded-cluster-config-servers.md#std-label-sharding-config-server), which are billed separately from the data-bearing servers.

On Atlas Infinite clusters, data-bearing servers don't apply. Atlas stores and manages your data in a storage layer that is separate from the compute layer. The electable, read-only, and analytics nodes are [compute nodes](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-compute-node) that access data in the storage layer. To learn more, see [MongoDB Atlas Infinite: Architecture.](https://www.mongodb.com/docs/atlas/infinite/atlas-infinite-architecture.md#std-label-atlas-infinite-architecture)

**Note:**

You might see different values depending on your selected cloud provider and region.

During public preview, Atlas Infinite clusters support the `M10`-`M60` General cluster tiers and the `M40`-`M60` Low-CPU cluster tiers. Atlas Infinite clusters don't support sharded clusters.

Atlas Core clusters support `M10+` General cluster tiers and `M40+` Low-CPU cluster tiers.

The following sections describe the differences between available cluster tiers.

### Free Clusters and Flex Clusters

Use Free clusters and Flex clusters as an economical way for getting started with MongoDB and for low-throughput applications. These clusters deploy to an environment with access to a subset of Atlas features. To learn more about Free cluster and Flex cluster limitations, see:

- [Atlas Free Cluster Limits](https://www.mongodb.com/docs/atlas/reference/free-shared-limitations.md#std-label-atlas-free-tier)

- [Atlas Flex Limitations](https://www.mongodb.com/docs/atlas/reference/flex-limitations.md#std-label-flex-cluster-limitations)

You can deploy one Free cluster (free sandbox replica set cluster) per Atlas project. You can [scale a Free cluster](https://www.mongodb.com/docs/atlas/scale-free-flex-cluster.md#std-label-scale-free-flex-cluster) to a Flex cluster or to a dedicated cluster at any time.

Flex clusters provide the following added features compared to Free clusters:

- [Backups](https://www.mongodb.com/docs/atlas/backup/cloud-backup/flex-cluster-backup.md#std-label-flex-snapshots) for your cluster data

- Increased storage

- [API access](https://www.mongodb.com/docs/atlas/api.md#std-label-graphql-api-overview)

When you create a Free cluster or a Flex cluster, you can select Atlas Infinite or Atlas Core. The selection doesn't change your Free cluster or Flex cluster. Atlas stores the selection and applies it when you scale the cluster tier to a dedicated cluster, where you can optionally select a different edition. To learn more, see [Scale a Free or Flex Cluster to a Dedicated Cluster.](https://www.mongodb.com/docs/atlas/scale-free-flex-cluster.md#std-label-scale-free-flex-cluster)

#### Considerations

Flex clusters don't have the full availability of features found in Dedicated clusters. To learn more, see [Limits on Atlas Cluster Types.](https://www.mongodb.com/docs/atlas/reference/limitations.md#std-label-limits)

### Dedicated Clusters for Low-Traffic Applications

`M10` and `M20` cluster tiers support development environments and production environments with low-traffic applications.

These cluster tiers support replica set deployments only, but otherwise provide full access to Atlas features.

**Note:**

`M10` and `M20` cluster tiers use burstable performance infrastructure. Cloud providers cap CPU usage after burst periods, which can cause throttling under heavy load. To learn more, see [How Atlas Scales Cluster Tier.](https://www.mongodb.com/docs/atlas/cluster-autoscaling-compute-core.md#std-label-howitworks-scale-cluster-tier)

### Dedicated Clusters for High-Traffic Applications

`M30+` clusters are recommended for production environments.

These cluster tiers support replica set and sharded cluster deployments with full access to Atlas features.

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.

### Gen2 Dedicated clusters

`M30+` Atlas Core clusters are available in [cluster generations](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-cluster-generation) Gen1 or Gen2 on AWS (Amazon Web Services) and Google Cloud. On Atlas Core clusters, Gen2 Dedicated clusters offer improved performance compared to Gen1 clusters and support Extended Standard IOPS (Input/Output Operations per Second), offering the following benefits:

- Optimized price performance.

- Newer hardware that enables long-term growth and avoids capacity restraints from older hardware.

- Independent scaling of your cluster's standard IOPS (Input/Output Operations per Second) and storage capacity with increased maximum standard IOPS (Input/Output Operations per Second) rates:

  - `80k` IOPS (Input/Output Operations per Second) for AWS (Amazon Web Services)

  - `160k` IOPS (Input/Output Operations per Second) for Google Cloud

`M30+` Atlas Infinite clusters are available on Gen2 only, and don't support Extended Standard IOPS (Input/Output Operations per Second). To learn more about how Atlas Infinite clusters handle storage and IOPS (Input/Output Operations per Second), see [Manage Storage on an Atlas Infinite Cluster](https://www.mongodb.com/docs/atlas/infinite/atlas-infinite-storage.md#std-label-atlas-infinite-storage) and [Atlas Infinite Storage IOPs and Throughput Values per Cluster Tier.](https://www.mongodb.com/docs/atlas/reference/amazon-aws.md#std-label-atlas-infinite-storage-iops-throughput-values)

When creating a new cluster through the Atlas UI, Atlas automatically selects the Gen2 option under the Cluster Tier section for eligible clusters. For an Atlas Core cluster, you can select Gen1 instead to deploy a Gen1 cluster.

**Tip: Setting a cluster's generation using the Atlas Administration API or Atlas CLI**

To specify a [cluster's generation](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-cluster-generation) using the Atlas Administration API or Atlas CLI, use the `instanceSize` or `--tier` options, respectively.

Gen1 clusters use only the cluster tier in their names in the API and CLI, while Gen2 clusters use the cluster tier with `_GEN_2` appended. For example, to deploy an `M30` tiered cluster:

- Use `M30` for a Gen1 `M30` cluster.

- Use `M30_GEN_2` for a Gen2 `M30` cluster.

If you update an existing Gen2 cluster with the [Update One Cluster in One Project](https://www.mongodb.com/docs/atlas/reference/api-resources-spec/v2/#operation/updateGroupCluster) endpoint, specify the corresponding `_GEN_2` value for the `instanceSize` field. A Gen1 value such as `M200` might unintentionally change the cluster's generation to Gen1.

For a list of AWS (Amazon Web Services) and Google Cloud cluster tiers that support Gen2 clusters, see:

- [AWS Gen2 Available Cluster Tiers.](https://www.mongodb.com/docs/atlas/reference/amazon-aws.md#std-label-aws-reference-gen2-cluster-tiers)

- [GCP Gen2 Available Cluster Tiers.](https://www.mongodb.com/docs/atlas/reference/google-gcp.md#std-label-gcp-reference-gen2-cluster-tiers)

For existing clusters, you can switch between generations in the same way you would change your cluster's tier. To learn more, see [Modify the Cluster Tier.](https://www.mongodb.com/docs/atlas/scale-cluster.md#std-label-scale-cluster-instance)

#### Considerations

Before using Gen2 clusters, consider the following limitations. You can also [Compare Gen1 and Gen2 Clusters.](https://www.mongodb.com/docs/atlas/manage-clusters.md#std-label-compare-cluster-generations)

- Gen2 clusters are available only on AWS (Amazon Web Services) and Google Cloud. Gen2 Dedicated clusters are not available on Azure (Microsoft Azure).

- Multi-cloud support is not available for Gen2 Dedicated clusters.

- Not all cloud provider regions support Gen2 Dedicated clusters. To learn more, see:

  - [AWS Gen2 Supported Regions](https://www.mongodb.com/docs/atlas/reference/amazon-aws.md#std-label-aws-reference-gen2-regions)

  - [GCP Gen2 Supported Regions](https://www.mongodb.com/docs/atlas/reference/google-gcp.md#std-label-gcp-reference-gen2-regions)

- Cross-region support is available only if all regions in which you deploy your cluster support Gen2 clusters on your chosen cloud provider.

- On Atlas Core clusters and Atlas Infinite clusters, `M10` and `M20` clusters are generation-agnostic. You don't select a [cluster generation](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-cluster-generation) when you deploy an `M10` or `M20` cluster.

- All nodes within a cluster must be of the same generation. You can't mix Gen1 and Gen2 nodes within the same cluster.

- When you update a cluster with the [Update One Cluster in One Project](https://www.mongodb.com/docs/atlas/reference/api-resources-spec/v2/#operation/updateGroupCluster) endpoint, specify an `instanceSize` that matches the cluster's intended generation. For example, `M200` is Gen1, while `M200_GEN_2` is Gen2. If you specify a Gen1 value for an existing Gen2 cluster, you might unintentionally change the cluster's generation. To keep the cluster on Gen2, specify the corresponding `_GEN_2` instance size, such as `M200_GEN_2`.

- Gen2 clusters support only reactive auto-scaling, not predictive auto-scaling. To learn more, see [Scaling a Gen2 Dedicated Cluster.](https://www.mongodb.com/docs/atlas/cluster-autoscaling-compute-core.md#std-label-reactive-autoscaling-gen2-cluster)

#### Compare Gen1 and Gen2 Clusters

The following table lists the differences between Gen1 and Gen2 cluster generations:

|  | Gen1 | Gen2 |
| --- | --- | --- |
| Storage and Standard IOPS (Input/Output Operations per Second) Expansion | Storage and Standard IOPS (Input/Output Operations per Second) scale **together** | Storage and Standard IOPS (Input/Output Operations per Second) scale **independently** |
| Maximum Standard IOPS (Input/Output Operations per Second) | Up to: `16k` IOPS (Input/Output Operations per Second) for AWS (Amazon Web Services); `100k` IOPS (Input/Output Operations per Second) for Google Cloud | Up to: `80k` IOPS (Input/Output Operations per Second) for AWS (Amazon Web Services); `160k` IOPS (Input/Output Operations per Second) for Google Cloud |
| Cluster Tiers | All tiers | `M30+` only |
| Cloud Providers | AWS (Amazon Web Services), Google Cloud, Azure (Microsoft Azure) | AWS (Amazon Web Services), Google Cloud |
| Region Availability | All regions for a given cloud provider | For AWS (Amazon Web Services), see [Gen2 Region Support](https://www.mongodb.com/docs/atlas/reference/amazon-aws.md#std-label-aws-reference-gen2-regions) For Google Cloud, see [Gen2 Region Support](https://www.mongodb.com/docs/atlas/reference/google-gcp.md#std-label-gcp-reference-gen2-regions) |
| Cross-Region Deployments |  | Only across regions that support Gen2 clusters for the cloud provider you are using. See: [AWS Gen2 Region Support](https://www.mongodb.com/docs/atlas/reference/amazon-aws.md#std-label-aws-reference-gen2-regions); [GCP Gen2 Region Support](https://www.mongodb.com/docs/atlas/reference/google-gcp.md#std-label-gcp-reference-gen2-regions) |
| Auto-scaling | Reactive and predictive auto-scaling | Reactive auto-scaling only on Atlas Core clusters. Atlas Infinite clusters support reactive and predictive auto-scaling. |
| Cross-Cloud Deployment Support |  | |
| [Billing](https://www.mongodb.com/docs/atlas/billing/cluster-configuration-costs.md#std-label-gen2-clusters-billing) | Storage and IOPS (Input/Output Operations per Second) scale together, so your bill reflects scaling for both. | Storage and IOPS (Input/Output Operations per Second) scale independently, so your bill only reflects what you scaled. |

A cluster's maximum IOPS (Input/Output Operations per Second) rate also depends on the tier and disk size. The maximum standard IOPS (Input/Output Operations per Second) rates listed are the highest IOPS (Input/Output Operations per Second) rates achievable through different tier and disk size configurations.

### Sharded Clusters

A sharded cluster distributes your data across multiple shards, each a replica set, to horizontally scale your Atlas deployment and efficiently handle growing data and workloads. To learn how to configure and manage sharding, see [Manage Cluster Sharding.](https://www.mongodb.com/docs/atlas/cluster-sharding.md#std-label-atlas-cluster-sharding)

You can use the Atlas Administration API to choose a different tier per shard in a sharded cluster. You can also select [Analytics node](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-analytics-node) tiers independently for each shard. The largest and smallest shard tiers must be within two tiers of each other. For example, if the largest shard is `M50`, the smallest shard can be `M30` or `M40`. If you change the cluster tier for a sharded cluster in the Atlas UI, Atlas changes the tier of all shards in the cluster.

You can also use the Atlas Administration API to choose different IOPS (Input/Output Operations per Second) per shard if the cluster is on AWS (Amazon Web Services) using AWS (Amazon Web Services) provisioned IOPS or the cluster is on Azure (Microsoft Azure) in regions that support Extended IOPS/storage.

Atlas Infinite doesn't support sharded clusters in public preview. For the features supported in public preview, see [Public Preview Availability.](https://www.mongodb.com/docs/atlas/infinite/atlas-infinite-landing.md#std-label-atlas-infinite-availability)

To learn more, see [Manage Cluster Sharding](https://www.mongodb.com/docs/atlas/cluster-sharding.md#std-label-atlas-cluster-sharding) and the [Update One Cluster in One Project](https://www.mongodb.com/docs/api/doc/atlas-admin-api-v2/operation/operation-updategroupcluster) endpoint in the Atlas Administration API documentation.

#### Limitations

Every shard must have an equal disk size on all nodes. NVMe (non-volatile memory express) clusters are not compatible with independent shard scaling.

### NVMe Storage

To use locally attached ephemeral NVMe (non-volatile memory express) SSD (Solid State Disk)s for applications that require low-latency, high-throughput I/O, see [NVMe Storage for Atlas Clusters.](https://www.mongodb.com/docs/atlas/nvme-storage.md#std-label-nvme-storage)

### Free, Flex, and Dedicated Cluster Comparison

The following table highlights key differences between Free clusters, Flex clusters, and Dedicated Atlas Core clusters.

|  | Free Clusters | Flex Clusters | Dedicated Clusters |
| --- | --- | --- | --- |
| Storage (Data Size + Index Size) | 512 MB | 5 GB | 10 - 4000 GB |
| MongoDB Version Support | 8.0 | 8.0 | 7.0, 8.0, 9.0, and Latest Version With Auto Upgrades |
| Metrics and Alerts | Limited | Limited | [Full metrics](https://www.mongodb.com/docs/atlas/monitor-cluster-metrics.md#std-label-monitor-cluster-metrics), including the [Real Time Performance Tab](https://www.mongodb.com/docs/atlas/real-time-performance-panel.md#std-label-real-time-metrics-status-tab), and full [alert configuration options.](https://www.mongodb.com/docs/atlas/configure-alerts.md#std-label-configure-alerts) |
| VPC Peering | No | No | [VPC Peering Connection wizard](https://www.mongodb.com/docs/atlas/security-vpc-peering.md#std-label-vpc-peering) |
| Global Region Selection | A subset of regions in AWS (Amazon Web Services), Google Cloud, and Azure. | A subset of regions in AWS (Amazon Web Services), Google Cloud, and Azure. | Atlas supports deploying clusters globally on [Amazon Web Services](https://www.mongodb.com/docs/atlas/reference/amazon-aws.md#std-label-amazon-aws), [Google Cloud Platform](https://www.mongodb.com/docs/atlas/reference/google-gcp.md#std-label-google-gcp), and [Microsoft Azure.](https://www.mongodb.com/docs/atlas/reference/microsoft-azure.md#std-label-microsoft-azure) |
| Cross-Region Deployments | No | No | Yes. Specify additional regions for high availability or local reads when [creating](https://www.mongodb.com/docs/atlas/tutorial/create-new-cluster.md#std-label-create-new-cluster) or [scaling](https://www.mongodb.com/docs/atlas/scale-cluster.md#std-label-modify-cluster) a cluster. |
| Backups | No | Yes, [daily backup snapshots](https://www.mongodb.com/docs/atlas/backup/cloud-backup/flex-cluster-backup.md#std-label-flex-snapshots) | Yes |
| Sharding | No | No | Yes, for clusters using an `M30+` tier |
| Dedicated Cluster | No, Free clusters run in a shared environment | No, Flex clusters run in a shared environment | Yes, `M10+` clusters deploy each [`mongod`](https://www.mongodb.com/docs/manual/reference/program/mongod.md#mongodb-binary-bin.mongod) process to its own instance. |
| Performance Advisor | No | No | Yes |
| BI Connector for Atlas | No | No | Yes |

For a complete list of Free cluster limitations, see [Atlas Free Cluster Limits.](https://www.mongodb.com/docs/atlas/reference/free-shared-limitations.md#std-label-atlas-free-tier)

To learn more, see [Auto-Scaling for Atlas Clusters.](https://www.mongodb.com/docs/atlas/cluster-autoscaling.md#std-label-cluster-autoscaling)

## Take the Next Steps

You can manage clusters in the following ways:

| Action | Description |
| --- | --- |
| [Customize Atlas Core Cluster Storage](https://www.mongodb.com/docs/atlas/customize-storage.md#std-label-create-cluster-storage) | Customize the storage capacity of your cluster. Each cluster tier comes with a default set of resources. `M10+` clusters provide the ability to customize your storage capacity. |
| [Manage Cluster Sharding](https://www.mongodb.com/docs/atlas/cluster-sharding.md#std-label-atlas-cluster-sharding) | Shard your cluster to scale horizontally. You can use the Atlas Cluster Builder UI, the latest version of the [Atlas Admin API](https://www.mongodb.com/docs/api/doc/atlas-admin-api-v2/group/endpoint-clusters), [Atlas CLI](https://www.mongodb.com/docs/atlas/cli/current/), or [HashiCorp Terraform MongoDB Atlas Provider](https://registry.terraform.io/providers/mongodb/mongodbatlas/latest) to shard your cluster. You can also use the latest version of the [Atlas Admin API](https://www.mongodb.com/docs/api/doc/atlas-admin-api-v2/group/endpoint-clusters) to independently scale each shard in your cluster. |
| [Auto-Scaling for Atlas Clusters](https://www.mongodb.com/docs/atlas/cluster-autoscaling.md#std-label-cluster-autoscaling) | Configure the cluster tier ranges that Atlas uses to automatically scale your cluster tier, storage capacity, or both in response to cluster usage. |
| [Configure Additional Settings](https://www.mongodb.com/docs/atlas/cluster-additional-settings.md#std-label-create-cluster-additional-settings) | Configure additional cluster settings such as MongoDB version, backup, and encryption options. |
| [Resource Tags](https://www.mongodb.com/docs/atlas/tags.md#std-label-configure-resource-tags) | Use resource tags that you provide and manage to categorize resources by purpose, environment, team, or billing center. |
| [Modify an Atlas Core Cluster](https://www.mongodb.com/docs/atlas/scale-cluster.md#std-label-modify-cluster) | Reconfigure an existing cluster. Modify any of the available Atlas configuration options. |
| [Upgrade Major MongoDB Version for a Cluster](https://www.mongodb.com/docs/atlas/tutorial/major-version-change.md#std-label-upgrade-major-MongoDB-version) | Manage major version upgrades for your cluster. Atlas enables you to upgrade the major version of an Atlas cluster at any time. |
| [Manage Cluster Maintenance](https://www.mongodb.com/docs/atlas/tutorial/cluster-maintenance-window.md#std-label-configure-maintenance-window) | Configure maintenance windows for your cluster. You can set the hour of the day that Atlas should start weekly maintenance on your cluster. |
| [Pause, Resume, or Terminate a Cluster](https://www.mongodb.com/docs/atlas/pause-terminate-cluster.md#std-label-pause-terminate-cluster) | Pause, resume, or terminate an existing cluster. You can't change the configuration of a paused cluster. Also, you can't read data from or write data to a paused cluster. |
| [Configure High Availability and Workload Isolation](https://www.mongodb.com/docs/atlas/cluster-config/multi-cloud-distribution.md#std-label-create-cluster-multi-region) | Configure multi-cloud distribution for increased availability. Atlas offers options to improve the availability and workload balancing of your cluster. |
| [Query using Pre-Defined Replica Set Tags](https://www.mongodb.com/docs/atlas/reference/replica-set-tags.md#std-label-replica-set-tags) | Use pre-defined replica set tags that Atlas provides to direct queries from specific applications to specific node types and regions. To use pre-defined replica set tags in your connection string and direct queries to specific nodes, set the tag in the `readPreferenceTags` connection string option. |