Microsoft Azure¶

Synopsis¶

Atlas supports deploying clusters onto Microsoft Azure. This page provides reference material related to Atlas cluster deployments on Azure.

Depending on your cluster tier, Atlas supports the following Azure regions. While all of the following regions support M10+ clusters, some regions don't support Free or Shared-Tier clusters. A check mark indicates support for Free clusters, Shared-Tier clusters, or Availability Zones. The Atlas Region is the corresponding region name used by Atlas processes.

Note

Regions with Availability Zones guarantee higher uptime for dedicated clusters deployed after September 12, 2019. Existing clusters in regions with Availability Zones are not automatically migrated. To learn more about Availability Zones, see Azure's documentation.

Azure Region	Location	Atlas Region
`centralus`	Iowa, USA	`US_CENTRAL`
`eastus`	Virginia (East US)	`US_EAST`
`eastus2`	Virginia, USA	`US_EAST_2`
`northcentralus`	Illinois, USA	`US_NORTH_CENTRAL`
`westus`	California, USA	`US_WEST`
`southcentralus`	Texas, USA	`US_SOUTH_CENTRAL`
`westus2`	Washington, USA	`US_WEST_2`
`westcentralus`	Wyoming, USA	`WEST_CENTRAL_US`
`brazilsouth`	Sao Paulo, Brazil	`BRAZIL_SOUTH`
`canadaeast`	Quebec City, QC, Canada	`CANADA_EAST`
`canadacentral`	Toronto, ON, Canada	`CANADA_CENTRAL`

Important

Due to their higher cost, it is recommended to use Switzerland West or UAE Central as a secondary disaster recovery (DR) region in a multi-region cluster if necessary.

Use Switzerland West in conjunction with Switzerland North.
Use UAE Central in conjunction with UAE North.

Cluster Configuration Options¶

Each Atlas cluster tier comes with a default set of resources. Atlas provides the following resource configuration options:

Custom Storage Size

The size of the server root volume. Atlas clusters deployed onto Azure use premium storage disks. [1]

Note

RAM Availability

The actual amount of RAM available to each cluster tier might be slightly less than the stated amount, due to memory that the kernel reserves.

The following clusters tiers are available:

Cluster Tiers	Default Storage	Default RAM
M2	2 GB	Shared
M5	5 GB	Shared
M10	32 GB	2 GB
M20	32 GB	4 GB
M30	32 GB	8 GB
M40	128 GB	16 GB
R40	128 GB	16 GB
M50	128 GB	32 GB
R50	128 GB	32 GB
M60	128 GB	64 GB
R60	128 GB	64 GB
M80	256 GB	128 GB
R80	256 GB	128 GB
M200	256 GB	256 GB
R200	256 GB	256 GB
R300	512 GB	384 GB
R400	512 GB	432 GB

Can use this tier for a multi-cloud cluster.

Not available in the following regions:

germanywestcentral
switzerlandnorth
switzerlandwest

Note

Cluster Tier & API Naming Conventions

For purposes of management with the Atlas API, cluster tier names that are prepended with R instead of an M (R40 for example) run a low-CPU version of the cluster. When creating or modifying a cluster with the API, be sure to specify your desired cluster class by name with the providerSettings.instanceSizeName attribute.

Important

Multi-Cloud Low-CPU clusters

Low-CPU cluster tiers (R40, R50, R60, etc) are available in multi-cloud cluster configurations as long as the cluster tier is available for all the regions that the cluster uses.

Workloads typically require less than 2TB.

Atlas configures the following resources automatically and does not allow user modification:

Storage Speed: The input/output operations per second (IOPS) [1] the system can perform. This value is fixed based on the specified custom storage size.
Encrypted Storage Volumes: Azure storage volumes are always encrypted.

Azure Fault Domains¶

Each Azure region includes a set number of fault domains. Fault domains consist of a group of virtual machines that share a common power source and network switch. For regions that have at least three fault domains (3FD), Atlas deploys clusters across three fault domains. For regions that only have two fault domains (2FD), Atlas deploys clusters across two fault domains.

The Atlas Add New Cluster form marks regions that support 3FD clusters as Recommended, as they provide higher availability.

The number of fault domains in a region has no effect on the number of MongoDB nodes Atlas can deploy. MongoDB Atlas clusters are always made of replica sets with a minimum of three MongoDB nodes.

For general information on Azure regions and fault domains, see Manage the availability of Windows virtual machines in Azure

Regions with at Least Three Fault Domains¶

If the selected Azure region has at least three fault domains, Atlas clusters are split across three fault domains. For example, a three node replica set cluster would have one node deployed onto each zone.

A 3-node replica set deployed across a 3-fault-domain Azure region.

3FD clusters have higher availability compared to 2FD clusters. However, not all regions support 3FD clusters.

Regions with Only Two Fault Domains¶

If the selected Azure region has two fault domains, Atlas clusters are split across the two fault domains. For example, a three node replica set cluster would have two nodes deployed to one zone and the remaining node deployed to the other zone.

A 3-node replica set deployed across a 2-fault-domain Azure region.

2FD clusters have a higher chance of loss of availability in the event of the loss of an zone than 3FD clusters. However, where latency or location are a priority, a region that supports 2FD clusters may be preferred.

[1]	(1, 2) For detailed documentation on Azure storage options, see High-performance Premium Storage and managed disks for VMs

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