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We’re thrilled to announce the public preview of Azure Spot Virtual Machines in Standby Pools for Virtual Machine Scale Sets (VMSS)—a powerful new capability that combines the elasticity of standby pools with the cost-efficiency of Spot pricing.

Why Spot VMs in Standby Pools?

Azure Spot VMs let you take advantage of unused Azure capacity at deep discounts. However, they come with the trade-off of potential eviction when Azure needs the capacity back. By integrating Spot VMs into standby pools, you can now pre-provision low-cost compute capacity that’s ready to quickly scale out—ideal for interruptible workloads like:

• Batch processing


• Dev/test environments


• Large-scale compute jobs


• Resilient microservices

How It Works

With this new capability, you can configure your standby pool to use Spot VMs. When a scale-out event occurs:

• Instances are pulled from the Spot standby pool into the scale set.


• These instances retain their Spot pricing and characteristics.


• If capacity is unavailable or Spot VMs are evicted, VMSS can fall back to provisioning new instances based on your scale set policy.

This gives you the flexibility to optimize for cost while still maintaining fast scale-out performance.

Key Considerations

• No SLA: Spot VMs do not come with availability guarantees.


• Eviction Policy: Using Spot Instances in a standby pool are only supported when using a delete eviction policy and with scale set deployments using 100% Spot Instances (Spot-Mix is not yet supported) 


• Capacity-Aware: Azure only allocates Spot VMs when capacity is available, so standby pool readiness may vary.

Getting Started

For more details, check out Use Spot Instances in standby pools (Preview)