Virtual machines (VMs) in Azure come in predefined sizes that are called families or  series.  An individual VM is often referred to as an instance.  

Different VM families are designed for common use –cases and are comprised of certain amounts of CPU cores and GB of RAM.  It’s not possible to arbitrarily mix and match CPU cores and GB of RAM as can be done with Hyper-V and VMware.  Therefore, it is important to understand the specific VM series you wish to deploy when thinking through the IT environment you are deploying in Microsoft Azure.  

Additionally, selecting the right VM for your host pools and user needs is one of the biggest ways to control and bring down costs in Azure. If you want to investigate other ways to bring down costs in Azure, check out this blog.  

Here, we will focus on four of the most common Azure VM series, how they compare to each other, and when to use each.  

Microsoft Azure VMs: B Series  

Economical burstable VMs *  

B-series are economical VMs that provide a low-cost option for workloads that typically run at a low-to-moderate baseline CPU utilization, but sometimes need to burst to significantly higher CPU utilization when the demand rises.   

We like B series for servers that are 24×7 and non-customer facing servers.   

When idle, the B series will bank credits and use those credits later when CPU utilization needs to burst past the baseline.  When rebooted, B series will lose their credits which can take hours to rebuild without too much impact.  When booted without any banked credits, the B series will only have access to allow for a small fraction of total CPU utilization until a bank of credits can be built up.   

Microsoft Azure VMs: D Series  

General purpose compute *  

D-series VMs feature fast CPUs and optimal CPU-to-memory configuration, making them suitable for most production workloads. DSv5-series instances carry more powerful CPUs and the same memory and disk configurations as the D-series. However, these CPU cores are hyper-threaded, meaning that a single physical CPU core is behind each two CPU cores in a Dsv5 VM.   

Dsv5 instances (ie. Ds4v_5 – 4 core x 16GB RAM) are the 3rd Generation Intel® Xeon® Platinum 8370C (Ice Lake) processor in a hyper threaded configuration, providing a better value proposition for most general-purpose workloads. This new processor features an all-core turbo clock speed of 3.5 GHz with Intel® Turbo Boost Technology, Intel® Advanced-Vector Extensions 512 (Intel® AVX-512) and Intel® Deep Learning Boost. The Ds-series supports Standard and Premium SSD storage.   

We like D series for performance as they pair well with premium SSD – a must for solutions or presentation layers that are customer-facing.  There is not a lot of difference in price with v5 instances (as opposed to v4 or v3), which makes them ideal.   

Example use-cases include many LOB applications, SQL databases, in-memory caching, and analytics. The latest generations are ideal for applications that demand faster CPUs, better local disk performance or higher memories.   

Microsoft Azure VMs: E Series  

Optimized for in-memory hyper-threaded applications* 

The E-series family of Azure VMs are optimized for heavy in-memory applications such as SQL Servers and AVD session hosts. These VMs are set up with high memory-to-core ratios, which makes them well-suited for relational database servers, with medium to large caches, and in-memory analytics. The E-series VMs range from 2 to 64 vCPUs and 16-432 GiB RAM, respectively. The Es-series supports Azure Premium SSDs.  

We like the E series for session hosts and collections where the line of business applications consumes a higher-than-normal memory footprint per user.  Software that is optimized for multi-user session hosts can often consume large footprints of memory.  

Example use cases include Application Servers, Database Servers, Azure Virtual Desktop session hosts 

Microsoft Azure VMs: N Series  

GPU enabled virtual machines *  

The N-series is a family of Azure VMs with GPU capabilities. GPUs are ideal for compute and graphics-intensive workloads, helping customers to fuel innovation through scenarios like high-end remote visualization, deep learning, and predictive analytics.   

The N-series has three different offerings aimed at specific workloads:   

• The NC-series is focused on high-performance computing and machine learning workloads. The latest version— NC A100 v4 —features NVIDIA’s A100 PCIe GPUs.   
• The ND-series is focused on training and inference scenarios for deep learning. The latest version – ND A100 v4 – features the NVIDIA Ampere A100 40GB Tensor Core GPUs 
• The NV-series enables powerful remote visualization workloads and other graphics-intensive applications backed by the NVIDIA A10 GPU.  NVadsA10 v5 – features AMD Gen3 CPU’s and NVIDIA A10 GPUs packing a powerful combination 

We like N series for graphic needs related to engineering and 3D modeling.  The footprint is quite large which makes them good shared machines.  Assigning 2-4 users per N series as an AVD Session Host is an ideal for cost distribution and performance requirements.  NV series will be the primary N series instance.  Approach other N series with a very specific need or application requirement as they are not a good fit for GPU enabled virtual desktops.  

Example use-cases include running applications like AutoCAD, SolidWorks, Revit, BlueBeam, Photoshop, Lumion.  

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