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Create a Cluster

MongoDB deployments, or “clusters” in Atlas, can be either a replica set or a sharded cluster.

Atlas also provides an option to deploy a single Free Tier replica set per group. A Free Tier cluster has configuration limitations compared to a paid Atlas cluster; see Atlas M0 (Free Tier) Limitations for more information.

An Atlas group can have multiple MongoDB clusters.

A unique AWS Virtual Private Cloud (VPC) is created for each Atlas group. All clusters for the group are deployed inside this VPC. This region-specific VPC is created for the Atlas group during the deployment of the group’s first cluster.

Create a Cluster

To create a cluster, go to the Clusters view and click the Add New Cluster or Build a New Cluster button. Configure your cluster as described in the steps below. As you build your cluster, Atlas displays the associated costs.

If no MongoDB user exists for your Atlas group, you will also create your first MongoDB user.

You must save the admin user and password or you will lose admin access to your MongoDB databases until you reset the password. If you choose to have Atlas generate the admin password, save the password when it is displayed since Atlas displays it only once.

1

Go to the Clusters view.

Go to the Clusters view and click the Add New Cluster or Build a New Cluster button.

2

Configure your cluster.

Atlas provides the configuration options described in the table below. As you make selections, Atlas displays the associated costs.

Free Tier

Atlas M0 (Free Tier) instances run in a shared environment with limited configuration options and operational restrictions. See Atlas M0 (Free Tier) Limitations.

Configuration Option Description
MongoDB Version

The MongoDB version [1] for your cluster. Atlas always deploys the cluster with the latest stable release of the specified version.

Atlas supports MongoDB 3.2 and MongoDB 3.4 with the WiredTiger storage engine. By default, Atlas uses MongoDB 3.4. You can specify the MongoDB version when you create a cluster. If a created cluster uses MongoDB 3.2, you can upgrade to MongoDB 3.4 when you scale a cluster.

As new maintenance releases become available, Atlas automatically upgrades to these releases via a rolling process to maintain cluster availability.

Important

You cannot downgrade a cluster from MongoDB 3.4 to MongoDB 3.2.

Cluster Name The name as it will appear in Atlas.
Region

The physical location of your MongoDB cluster. The region you choose can affect network latency for clients accessing your databases. Regions marked as Recommended provide higher availability compared to other regions.

For more information on Recommended AWS regions, see Amazon Availability Zones.

The region selected for the first cluster in the Atlas group determines the region for all clusters in that group. This is because a region-specific Virtual Private Cloud (VPC) is created for the Atlas group during the deployment of the group’s first cluster.

Pricing for cluster configuration settings vary by region.

Instance Size

The memory, storage, and IOPS specification for each data-bearing server [2] for your Atlas cluster.

Atlas provides various instance sizes to support different use cases:

  • For development environments and low traffic websites, M0, M10 and M20 instance sizes.
  • For production environments that support high traffic applications or large datasets, M30 or larger instances sizes.

Each instance size comes with a default set of resources, but you can modify the following:

  • Custom Storage Capacity: The size of the server root volume. Changes to storage capacity affects cost.
  • Custom Storage Speed: The input/output operations per second (IOPS) the system can perform. Changes to storage speed affects cost.
  • Use encrypted storage volumes: Encrypts root volume using Amazon EBS encryption for data at rest inside the volume and all data moving between the volume and the instance.

For a sharded cluster, the selected instance size must be M30 or larger.

Replication Factor

The number of replica set members. Each member keeps a copy of your database, providing high availability and data redundancy.

Replica sets deployed in a Recommended region span three availability zones. Replica sets deployed in other regions span two availability zones. The number of availability zones in a region has no affect on the number of nodes Atlas can deploy. For more information on how Atlas deploys replica sets across availability zones, see Amazon Availability Zones.

Each member of the replica set runs on a separate instance. For details on how the number of server instances affects cost, see Number of Servers.

If your deployment is a sharded cluster, each shard is a replica set, and the replica factor determines the number of members in each shard replica set.

For more information on replica sets, see Replication in the MongoDB manual.

Do you want a sharded cluster?

Sharded clusters support horizontal scaling and consists of shards, config servers and router programs.

For a sharded cluster, the selected instance size must be M30 or larger.

  • Atlas deploys each shard as a replica set, consisting of the number of members specified by the replication factor. The shard servers have the selected instance size.
  • Atlas deploys the config servers as a three-member replica set. The config servers run on M30 instances.
  • Atlas deploys six routers (mongos programs) for a sharded cluster. Atlas runs the routers on the shard servers.

Each mongod process is deployed to its own AWS EC2 instance. For sharded clusters, the six routers (the mongos processes) run on six of the shard servers; i.e. each of the six mongos processes shares an AWS EC2 instance with one mongod process.

For details on how the number of server instances affects cost, see Number of Servers.

For more information on sharded clusters, see Sharding in the MongoDB manual.

Do you want to enable backup? If enabled, Atlas takes snapshots of your databases at regular intervals and retains them according to your group’s retention policy.
Admin Username & Password

Creates a MongoDB admin user with the specified username and password. These fields appear only if no MongoDB user exists for your Atlas group, such as if you are creating the first cluster in the group and have not set up MongoDB users beforehand.

When creating a new admin user, be sure to save the credentials.

The admin user has read and write access to any MongoDB database in any cluster in your Atlas group. The admin user can also enable sharding.

To have Atlas generate the password for the admin user, click Autogenerate Secure Password. If you choose to have Atlas generate the password, Atlas displays it only once.

3

Save your admin credentials.

Important

If you have created a new MongoDB admin user, you must save the admin user and password or you will lose administrative access to your MongoDB databases until you reset the password.

4

Enter Payment Information.

Click Confirm & Deploy to enter payment information.

You can terminate the cluster at any time using the following procedure:

  1. Click Clusters.
  2. For the cluster you want to terminate, click on the ... in the top-right corner.
  3. Click Terminate.

Atlas executes the terminate operation after completing any in-progress deployment changes.

Atlas M0 (Free Tier) Limitations

The following table lists the configuration limitations of Free Tier clusters:

Configuration Option Limitation
AWS Region Atlas deploys Free Tier clusters in us-east-1 (N. Virginia). This does not affect other clusters in the Atlas group.
MongoDB Version Version is set to MongoDB 3.4 with Wired Tiger and cannot be modified.
Instance Size You must select the M0 instance size to deploy a Free Tier cluster.
Instance Memory You cannot configure memory for a Free Tier cluster.
Instance Storage Storage is set to 512 MB and cannot be modified.
Replication Factor Replication Factor is set to 3 Nodes and cannot be modified.
Do You Want A Sharded Cluster You cannot deploy a Free Tier cluster as a Sharded Cluster.
Do You Want To Enable Backup You cannot enable backups.

The following table lists the operational limitations of Atlas Free Tier clusters:

Aggregation Atlas Free Tier clusters do not support the allowDiskUse option for the aggregation command or its helper method.
Throughput Maximum of 100 operations per second.
Connections Maximum of 100 connections.
Network bandwidth Restricted to 1GB per week in and 1GB per week out. Atlas throttles traffic to 1KB/s after reaching either bandwidth limit.
Javascript Free Tier clusters do not support server side javascript. For example, $where and map-reduce are not supported.
Migrating to a Paid Cluster

The Atlas UI does not provide an automated feature for migrating Free Tier data to a paid cluster.

For a tutorial on manually migrating Free Tier data to a paid cluster, see Migrate Data from an M0 (Free Tier) Cluster to a Paid Cluster.

Data Explorer Data Explorer is not available for a Free Tier cluster.
API Access You cannot modify or configure a Free Tier cluster using the Clusters API endpoint.
Number of Free Tier clusters You can deploy at most one Free Tier cluster per Atlas group.
Database Commands

Certain database commands are unsupported or behavior differently in a Free Tier cluster. See Command Limitations in Free Tier Clusters for more information.

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

Atlas Monitoring

The Metrics view of a Free Tier cluster only displays the following metrics:

  • Connections
  • Logical Size
  • Network
  • Opscounter

For more information on these metrics, see Real Time Metrics.

Database Names Free Tier clusters limit the name of a database, including the db prefix, to 63 bytes.
Database and Collections Maximum of 100 databases and 500 collections total.
Cluster Persistance Atlas may terminate idle Free Tier clusters as per the Terms of Service.
VPC Peering Free Tier clusters do not support VPC peering.

Terminate a Cluster

To terminate an Atlas cluster, do the following:

  1. Click Clusters.
  2. For the cluster you wish to terminate, click on the ... in the top-right corner.
  3. Click Terminate.

Atlas executes the terminate operation after completing any in-progress deployment changes.

Atlas bills for the hours that the cluster was active. See Billing for more information on Atlas billing.

Warning

Terminating a cluster also deletes any backup snapshots for that cluster. See Retention Policy.

Next Steps

To continue setting up the cluster, see:

To change the cluster configuration after deployment, see Scale a Cluster.

[1](1, 2) Atlas does not support MongoDB Enterprise deployments.
[2](1, 2) For replica sets, the data-bearing servers are the servers hosting the replica set members. For sharded clusters, the data-bearing servers are the servers hosting the shards. For sharded clusters, Atlas also deploys servers for the config servers; these are charged at a rate separate from the instance costs.