Understanding Azure Spot VMs

So-called Spot VMs allow customers to pay a discounted rate for certain Azure VMs that become available depending on Azure demand, with costs that vary as demand increases or decreases. Spot VM prices can be significantly lower than standard prices, with discounts from 30% to as high as 90% off normal pay-as-you-go (PAYG) costs, and customers agree to a maximum price when the VMs are deployed. After a VM is deployed with a Spot VM discount, customers can view a history of spot pricing for the specified VM size. Workloads are evicted with 30 seconds notice when the price rises above the maximum price selected by the customer or if Azure no longer has available Spot VM capacity. Spot VMs have no service level agreement (SLA) or availability guarantee due to their reliance on unused Azure capacity.

Spot VMs could be useful for certain applications, such as low-priority batch processing jobs that can be interrupted intermittently and do not have strict performance requirements, stateless workloads such as Web applications, and large distributed compute jobs that are designed to be fault-tolerant of individual node failures.