Manage Global Clusters
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Important
Feature unavailable in Serverless Instances
Serverless instances don't support this feature at this time. To learn more, see Serverless Instance Limitations.
Use the following resources to configure and manage your Global Clusters. For general cluster configuration, see Manage Clusters.
Atlas Global Clusters require that you define single or multi-region Zones, where each zone supports write and read operations from geographically local shards. You can also configure zones that support global low-latency secondary reads. To learn more about Global Cluster zones and how to configure them, see Global Write Zones and Zone Mapping.
Global Write Zones and Zone Mapping
Each Atlas Global Cluster supports up to nine distinct zones. Each zone consists of one Highest Priority region and one or more Electable, Read-only, or Analytics regions. The available regions depend on the selected cloud service provider.
Region Type | Description |
|---|---|
Highest Priority | Region where Atlas deploys the primary replica set member for the shard or shards associated with that zone. Clients can issue only write operations to the primary. Atlas uses the geographic location of the Highest Priority regions to construct a map of geographically-near countries and subdivisions. The Global Writes cluster uses this map for directing write operations to the correct zone. To facilitate low-latency local secondary reads of globally distributed data, for each zone in the cluster, add a Read-only node in the Highest Priority region of every other cluster zone. |
Electable | Region where Atlas deploys the electable secondary
replica set members for the shard or shards associated to that
zone. Electable regions add additional fault
tolerance in the event of a partial or total regional outage in
the Highest Priority region. |
Read-only | Region where Atlas deploys the non-electable
secondary replica set members for supporting secondary
read operations. |
Analytics | Region where Atlas deploys
analytics nodes. Analytics
nodes are read-only nodes configured with distinct
replica set tags. You can use these
tags to direct queries to specific regions. As a result,
analytics nodes can help isolate reporting queries from your
normal operational workload as well as reduce latency for local
reads. |
Shard Distribution
For each shard associated to a zone, Atlas distributes the shard nodes across the configured regions. If your cluster is located in a large geographic continent, create multiple zones to direct global writes to shards that are closer to your users.
Note
Atlas supports up to 100 shards per sharded cluster regardless of the number of zones. If you have requirements for more shards in your Global Cluster, contact support:
In Atlas, go to the Project Support page.
If it's not already displayed, select the organization that contains your desired project from the Organizations menu in the navigation bar.
If it's not already displayed, select your desired project from the Projects menu in the navigation bar.
Next to the Projects menu, expand the Options menu, then click Project Support.
The Project Support page displays.
The Atlas cluster builder includes templates for automatically configuring Global Writes zones for the Global Cluster. Each template provides a visual description of the cluster zone configuration, including estimates of geographic latency and coverage.
Configure Zone Mappings
Before you can configure zone mappings for a Global Cluster, you must create a Global Cluster.
To configure your existing Global Cluster:
In Atlas, go to the Clusters page for your project.
If it's not already displayed, select the organization that contains your desired project from the Organizations menu in the navigation bar.
If it's not already displayed, select your desired project from the Projects menu in the navigation bar.
If it's not already displayed, click Clusters in the sidebar.
The Clusters page displays.
Configure your existing Global Cluster.
Click Edit Config and select the cluster you want to modify from the drop-down menu.
In the dialog box that appears, complete the steps to configure your zones.
Note
Atlas doesn't automatically configure or shard collections. You can use the Atlas UI to shard a global collection for global writes if your global cluster uses Atlas-Managed Sharding and the collection meets the compatibility requirements.
Considerations
If you are using the standard connection string format rather than the DNS seedlist format, removing an entire zone from an existing global cluster may result in a new connection string.
To verify the correct connection string after deploying the changes:
In Atlas, go to the Clusters page for your project.
If it's not already displayed, select the organization that contains your desired project from the Organizations menu in the navigation bar.
If it's not already displayed, select your desired project from the Projects menu in the navigation bar.
If it's not already displayed, click Clusters in the sidebar.
The Clusters page displays.