Microsoft Publishes Some Details on the New Azure B-Series VMs

Last week I blogged about how the pricing of a new B-Series (burstable CPU) virtual machine appeared online. At the time, we knew almost nothing about the machines other than their intended workloads: anything with normally low CPU utilization that could temporarily burst, such as test/dev or low-end web/application servers.

While updating an article for, I found that the official specs of Azure VMs had been updated to include the B-Series:

The B-Series provides these customers the ability to purchase a VM size with a price conscience baseline performance that allows the VM instance to build up credits when the VM is utilizing less than its base performance. When the VM has accumulated credit, the VM can burst above the VM’s baseline using up to 100% of the CPU when your application requires the higher CPU performance.

That means that this is very similar to the AWS T2 Instances. By default, your machine’s CPU is artificially capped. By underutilizing the CPU, the machine can earn & bank credits that can be later used. This bank has a hard limit, depending on the size of the machine. Should the service in the machine need more CPU, those credits can be burned to go beyond the artificial cap to use the underlying physical cores potential. In other words, the less you use the CPU, the more horsepower you get for those times when you need it.

Here are some details on the sizes in the B-Series.

  • All of the machines are S-variants
  • Each machine has a small amount of SSD temporary storage.
  • Note how the disk stats refer to “max local disk”. Hmm!


Right now, there is a limited access preview for the B-Series in just a few regions:

  • West Europe
  • West US 2
  • East US
  • Asia Pacific – Southeast

I can see the B-Series in my subscriptions, but I cannot deploy it – the quota is set to 0 and the blade for requesting an increase does not include the B-Series. I guess this is still a private preview for now, and things might change on Sept 25th (Ignite).

4 thoughts on “Microsoft Publishes Some Details on the New Azure B-Series VMs”

  1. This is great information. Many On prem Dynamics virtual server owners want to test out their deployments in Azure. This may be great to test the viability. With heavily customized CRM 2013/CRM 2015 instances out there, this could get them in the cloud and allow more time to getting their customizations working in Dynamics 365. Thanks

  2. The table above on B-series is spot on – however there never seems to be a consistent place to obtain that simplified output unless you traverse several pages. Does Azure have an API/call type resource that will produce output for every azure instance and its characteristics. Example: when i want to see if AWS has anything new, new pricing – i can simply goto URL: and it will provide me with a consistent file i can use for analysis and such. Again – great read and glad i found the blog.

    1. I don’t know if there is anything public. As a CSP distributor, my employer can download a complete Excel price file for Azure, and that includes a “What’s New” worksheet.

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