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Microsoft has placed Azure Spot Virtual Machines (VMs), which provide access to unused Azure compute capacity, into preview.
Outlined in a blog post by Varun Shandilya, principal product manager for Azure Compute, Azure Spot VMs are available in the preview period at discounts of up to 90 per cent when compared to pay-as-you-go prices, with spot pricing for single VMs and VM Scale Sets (VMSS).
The prices for Spot VMs will depend on capacity for a size or SKU in an Azure region, according to the blog post, and are capped at PAYG prices.
“Spot pricing can give you insights into the availability and demand for a given Azure VM series and specific size in a region,” Shandilya wrote.
“The prices will change slowly to provide stabilisation, thus allowing you to better manage budgets.
“In the Azure portal, you will have access to the current Azure VM Spot prices to easily determine which region or VM size best fits your needs.”
According to Shandilya, Spot VMs have the same capability as PAYG VMs, except for pricing and evictions; Spot VMs are able to be evicted to make room for extra Azure capacity and if price caps are exceeded.
In order to prepare for an eviction, users are able to opt into a 30 second eviction notice.
To deploy the Spot VM, users can do so similarly to deploying a regular VM; by selecting Azure Spot Instance to deploy a Spot VM, where the maximum price and cap can also be defined
If the cap exceeded, Azure will evict the VM. If users want to avoid being evicted in this manner, they can leave the price uncapped.
If users wish to lower their costs and do not require specific VMs or Azure region, they can opt in for cheaper VMs or Azure regions.
Azure is also providing a separate quota for Spot VMs and Spot VMSS, separate to the PAYG VM quota.
Some applications for Spot VMs include batch jobs, interruption-immune workloads, development and tests and stateless applications that need to scale out.
The preview for Spot VMs will be replacing the preview of Azure low-priority VMs on scale sets, with eligible low-priority VMs automatically transitioning over.
As a result, Azure low-priority VMs will be discounted and retired after 1 January 2020.
