May 12 2020
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Today we’re announcing the general availability of Azure Spot Virtual Machines (VMs). Azure Spot VMs provide access to unused Azure compute capacity at deep discounts. Spot pricing is available on single VMs in addition to VM scale sets (VMSS). This enables you to deploy a broader variety of workloads on Azure while enjoying access to discounted pricing compared to pay-as-you-go rates. Spot VMs offer the same characteristics as a pay-as-you-go virtual machine, the differences being pricing and evictions. Spot VMs can be evicted at any time if Azure needs capacity.

The workloads that are ideally suited to run on Spot VMs include, but are not necessarily limited to, the following:

  • Batch jobs.
  • Workloads that can sustain or recover from interruptions.
  • Development and test.
  • Stateless applications that can use Spot VMs to scale out, opportunistically saving cost.
  • Short lived jobs which can easily be run again if the VM is evicted.

Spot VMs have replaced the preview of Azure low-priority VMs on scale sets. Eligible low-priority VMs have been automatically transitioned over to Spot VMs.

Spot Virtual Machine pricing

Unlike low-priority VMs, prices for Spot VMs will vary based on capacity for size or SKU in an Azure region. Spot pricing can give you insights into the availability and demand for a given Azure VM series and specific size in a region. The prices will change slowly to provide stabilization, 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. Spot prices are capped at pay-as-you-go rates.

VM size pane in portal showing VM sizes and spot prices in the region.
 

Deployment of Spot Virtual Machines

Spot VMs are easy to deploy and manage. Deploying a Spot VM is similar to configuring and deploying a regular VM. For example, in the Azure portal, you can simply select Azure Spot instance to deploy a Spot VM. You can also define your maximum price for your Spot VMs. You get a couple of options:

  1. You can choose to deploy your Spot VM without capping the price. Azure will charge you the Spot VM price at any given time, giving you piece of mind that your VMs will not be evicted for price reasons.
      Select capacity only eviction type.
  2. Alternatively, you can decide to provide a specific price to stay within your budget. Azure will not charge you above the maximum price you set and will evict the VM if the spot price rises above your defined maximum price.
       Ability to provide maximum price to deploy Spot VM.
     

There are a few other options available to lower costs:

  1. If your workload does not require a specific VM series and size, then you can find other VMs in the same region that may be cheaper.
  2. If your workload is not dependent on a specific region and you do not have data residency requirements, then you can find a different Azure region to reduce your cost.

Quota for Spot VMs

As part of this announcement, to give better flexibility, Azure is also rolling out a separate quota for Spot VMs that is separate from your pay-as-you-go VM quota. The quota for Spot VMs and Spot VMSS instances is a single quota for all VM sizes in a specific Azure region. This approach will give you easy access to a broader set of VMs.
   Request new quota for Spot VMs.

Handling evictions

Azure will try to keep your Spot VM running and minimize evictions, but your workload should be prepared to handle evictions as runtime for an Azure Spot VMs and VMSS instances is not guaranteed. You can optionally get a 30-second eviction notice by subscribing to scheduled events. Your VMs can be evicted due to the following reasons:

  1. Spot prices have gone above the max price you defined for the VM. Azure Spot VMs get evicted when the Spot price for the VM you have chosen goes above the price you defined at the time of deployment. You can try to redeploy your VM by changing prices.
  2. Azure needs to reclaim capacity.

In both scenarios, you can try to redeploy the VM in the same region or availability zone.

Best practices

Here are some effective ways to best utilize Azure Spot VMs:

  • For long running operations, try to create checkpoints so that you can restart your workload from a previously known checkpoint to handle evictions and save time.
  • In scale-out scenarios, to save costs, you can have two VMSS, where one has regular VMs and the other has Spot VMs. You can put both in the same load balancer to opportunistically scale out.
  • Listen to eviction notifications in the VM to get notified when your VM is about to be evicted.
  • If you are willing to pay up to pay-as-you-go prices then use Eviction type to Capacity Eviction only, in the API provide -1 as max price as Azure never charges you more than the Spot VM price.
  • To handle evictions, build a retry logic to redeploy VMs. If you do not require a specific VM series and size, then try to deploy a different size that matches your workload needs.
  • While deploying VMSS, select max spread in portal management tab or FD==1 in the API to find capacity in a zone or region.

Customer success stories

We are pleased with the feedback customer and partners are providing, and we plan to extend the capabilities of this offering to meet the needs of our stakeholders.

rescale_logo “We constantly hear from our customers that they want flexibility in their HPC environment. Flexibility in VM types, available capacity, and even up-front commitment. Azure’s Spot offering is exciting because it provides that flexibility, which combined with Rescale provides cost efficiencies and reduced preemption risk.” Gerhard Esterhuizen, VP of Engineering at Rescale and Brian Tecklenburg, VP of HPC Marketing at Rescale

“We benchmark performance across cloud providers, and Azure has consistently been among the top performers. Azure Spot VMs now allow our customers to use the best infrastructure available in an ad-hoc fashion. Azure Spot VMs, combined with Rescale’s HPC job orchestration and automated checkpoint restarts, help mitigate preemption risks. As a result, our customers can finally use the best cloud infrastructure, whenever they want.” Mulyanto Poort, VP of HPC Engineering at Rescale

 

InMobi_blue “InMobi runs one of our largest platforms, the InMobi Exchange, entirely on Azure. Having a cost-effective, cloud-native solution supporting high degrees of concurrency and scale was critical for our business, as the InMobi Exchange frequently finds itself catering to fluctuating traffic curves given the seasonal nature of the digital advertising industry. Leveraging the Azure Spot VM offerings, we’ve been able to rewire our application stack to be fully stateless and it’s been a real game changer with respect to making it cost efficient . Since InMobi was one of the early adopters of the Spot VM offering, we’ve found Microsoft to be excellent partners in ensuring the product evolves to meet our required levels of scale and functionality. As of now, we’ve moved the majority of our serving and data processing compute needs to Azure Spot VMs. And by doing so, we have been able to realize nearly 50-60 percent cost efficiencies on our compute needs, and that’s been a massive help in making our business more economically efficient.” Prasanna Prasad, Senior Vice President, Engineering, InMobi

Learn more about Azure Spot Virtual Machines

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