Availability Sets and Zones

Terminology

  • Availability Zone is a common cloud concept that refers to the logical grouping of resources. Each cloud can have one or more availability zones.

  • Availability Set is a Workload Manager-specific concept to denote a group or list of availability zones.

    Cloud Nuances

    Be aware of the nuances that the following table describes when configuring Availability Sets using the CCM UI or the Workload Manager REST APIS:

    Supported CloudCloud ReferenceWorkload Manager Concept
    AzureRM

    Concept of Availability Set

    (does not include Availability Zones)

    Workload Manager provides this input as a boolean value to enable/disable Azure's Availability Set concept.

    AWS

    Concept of Availability Zone 

    (includes Availability Sets)
    Workload Manager provides this input via the VPC NIC(s) field.
    OpenStack

    Concept of Availability Zone

    (includes Availability Sets)
    Workload Manager provides this input via the Availability Zone(s) field.
    Google

    Concept of Availability Zones

    (includes Launch Zones)
    Workload Manager provides this input via the Launch Zone field.

    This feature is only supported for these clouds.

Clustered VMs in an Application Tier

When an application tier is in a clustered environment (with more than one VM), then all the VMs in the cluster may need to be launched into the same availability zone. An availability set refers to a group or list of availability zones and ensures that the cluster VMs are evenly distributed across the specified zones using a Round-Robin implementation. Consequently, even during scaling operations (up or down), the VMs continue to be scaled across the zones. This feature is specific to each tier within an application.

For example, if a tier is a cluster of 3 VMs (being the minimum) and you have the availability set as zone1 and zone2, then when the job is launched the first node is launched into zone1, the second node into zone2, and the third node again into the zone1. After a successful job deployment, if you scale up the tier, then a new node is launched to zone2.

Configuration Details

This section provides the related images if configuring using the UI.

  • See Setup Deployment Environments > Adding a Deployment Environment > Cloud and Network Settings section to deploy to each supported cloud.

  • See Deployment Environment Defaults tab> Configure Default Settings > Cloud and Network Settings section to set defaults for each supported cloud.

See the following table for cloud-specific configuration details.

CloudUI ImageAPI Details when configuring cloudProperties
OpenStack

See OpenStack Configurations > Availability Zones and Sets
AWS

See AWS ConfigurationsAvailability Zones and Sets

AzureRM

See AzureRM Configurations > Availability Zones
Google

See Google Cloud Configurations > Launch Zones
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