Microsoft Azure VM Scale Sets

What is Microsoft Azure Virtual Machine (VM) Scale Sets?

Microsoft Azure Virtual Machine Scale Sets is a way to configure and manage large numbers of Windows and Linux VMs within the Microsoft Azure public cloud as a single unit. By using scale sets, IT administrators can easily create and manage a group of load-balanced VMs in Azure at any scale, across multiple availability zones (AZ) and fault domains and respond quickly to changing demand.

Exploring Azure VM Scale Sets

Azure VM Scale Sets is Microsoft service that helps enterprise teams create and manage large groups of heterogeneous VMs in the Azure cloud for Windows and Linux environments. A scale set for a web application might include web servers, application servers, database servers, network address translation servers (NAT), load balancing and other functionalities. With Azure VM Scale Sets, enterprise IT and cloud admins can deploy all these instances as a unit to organize and manage VMs as higher-level services instead of cobbling them together manually. They can also access and interact with individual VMs if necessary to monitor and tweak the individual instances.

Scale sets provide built-in load balancing and flexible orchestration to increase application availability, maintain fault domain isolation and ensure a unified user experience across the entire Azure VM ecosystem. Enterprise admins can distribute their applications across multiple availability zones and fault domains to enhance application security and resiliency. These applications can be stateful or stateless. Admins can also increase or decrease the number of VMs automatically depending on demand or aligned to a business-defined schedule.

Scale sets support stateless web front ends, container orchestration and microservices clusters. They are most suitable for large-scale computing services that can benefit from processing tasks distributed across multiple VMs. Examples include big data processing and customer-facing web or mobile applications. Scale sets are also useful for running Azure Kubernetes Service and Azure Service Fabric.

Why use Azure VM Scale Sets?

Many organizations need to run quorum-based or stateful workloads where fault domain isolation is essential. At the same time, their teams need to scale out applications while maintaining high availability and resilience. Azure VM Scale Sets supports all these needs.

Scale sets are especially beneficial in enterprise settings where applications run across many VMs and are distributed across multiple instances. Admins get built-in capabilities to easily manage and optimize these applications. The service supports up to 1,000 VM instances for standard marketplace images and custom images through the Azure Compute Gallery.

When many VMs run an application, it can be difficult to maintain a consistent configuration across the Azure environment, especially in terms of the VM size, disk configuration and application installs. By leveraging scale sets, organizations can ensure that these elements match across all VMs, thus increasing the likelihood that every application performs reliably.

A diagram of virtualized architecture
Multiple VMs, each running its own applications and guest OS, can share the same hypervisor, host OS and underlying host hardware.

Scale sets also provide automatic resource scaling and traffic load balancing. Organizations that expect to experience demand spikes for their applications and want to reduce costs and efficiently create Azure resources could benefit from this capability. Resource scaling means that scale sets will automatically increase or decrease the number of VM instances, so applications can scale automatically as demand changes. Even when demand is low, performance will not be affected since scale sets will minimize the number of unnecessary VM instances that run the application. When demand increases, additional VM instances are automatically added to maintain acceptable performance.

Scale sets also facilitate high application resiliency. Since a scale set can be used to run multiple instances, a problem in one instance will not affect availability. If anything, customers or end users can continue to access the application through one of the other VM instances with minimal interruption or latency.

Benefits of Azure VM Scale Sets

Azure VM Scale Sets provide an automated, flexible and scalable way to create and deploy thousands of VMs in Azure in just a few minutes. Admins can also take advantage of customizable metrics to easily manage the VM pool and consistently control and deploy VM updates.

Scale sets support easily configurable orchestration to distribute VMs across multiple AZ or fault domains. They ensure high availability and application resiliency. Built-in autoscaling means enterprise applications will automatically scale as the organization’s resource demand or schedule changes. Automated fault domain isolation ensures that businesses can run any quorum-based or stateful workload in the Azure cloud.

In summary, Azure VM Scale Sets benefit enterprise teams running workflows in the Azure cloud because they do the following:

  • Ease creation, management and updates for thousands of VMs centrally and at any scale.
  • Support large-scale services for batch, big data, and container workloads.
  • Create centralized templates that simplify load balancing and autoscaling as well as enable consistent application rollout.
  • Increase the availability of both stateful and stateless applications through AZ and fault domains.
  • Accommodate wide range of VM images and consumption models to fit various business needs and use cases.
  • Automatically issue OS updates to improve compliance and application security.
  • Offer up to 99.99% service-level agreements (SLAs) for VMs.
  • Lower costs by up to 90% compared to pay-as-you-go rates.

How Azure VM Scale Sets decrease VM complexity and optimize costs

With their flexible orchestration mode, Azure VM Scale Sets give enterprise teams full control of individual VMs to reduce management complexity. This mode also ensures high availability at scale and increased operational agility since the size of VMs can be changed without redeploying the scale set. The same application programming interfaces can be used to manage VMs and VM scale sets. Defining fault domains during the VM creation process accelerates and simplifies VM deployments.

Teams and their admins can optimize cloud costs by mixing Azure Spot VMs and pay-as-you-go VMs in the same scale set and by minimizing the number of unnecessary VM instances when demand is low. They can achieve additional savings by using existing licenses to run Windows Server VMs on Azure with Azure Hybrid Benefit and combining Azure Reserved VM instances with Azure Hybrid Benefit.

Scale sets also reduce infrastructure management cost and complexity by integrating with other Azure networking resources, such as Azure Load Balancer. Integrations let teams spread their workloads across the VMs in their scale sets. They can also troubleshoot issues by configuring NAT rules to connect to specific VM instances.

Learn when you should use Azure VM Scale Sets and see 5 methods to restore an Azure VM.

This was last updated in May 2023

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