How do you choose the right VM size in Azure?

If your business has finally decided to migrate from an on-premises location to a cloud computing platform, you will know that the transition can be a daunting one. There are a number of things that you will have to consider like the cloud provider, cloud deployment type, cloud capacity etc. In a previous article, we discussed how to choose the right cloud service for your business.  In this article, we’ll discuss some details of Microsoft Azure, Azure VM, how to choose Azure VM size etc.

Microsoft Azure is a very popular cloud computing platform that allows users to access and manage the resources and services provided by Microsoft. Around 80% of Fortune 500 companies use Azure. It has a very wide range of VM sizes and types. Although this may seem like a good thing, it can lead to some confusion about which VM size is the best one for your requirements.

Why do you need to choose the right VM size?

Microsoft Azure provides various types of Virtual Machines (VM) and have classified them based on the memory, storage and compute types. Usually, the VM size is dependent on the type of virtual machine that is being used.

A lot of companies make an intuitive decision on the VM size that they would like to use. However, this can prove to be a fatal mistake. Choosing the right VM size is crucial for the proper functioning of the application. It also helps reduce any additional costs that may be incurred. This is why businesses need to take several factors into consideration before selecting a particular size. A few important factors would include the number of CPUs, RAM capacity, the disk size and speed etc.

Different Types of Azure VMs

In order to choose the right VM size, it is important to gain an understanding of the various types of virtual machines that are available for use in Azure. Generally, the types vary according to whether the users need to run Windows or Linux and workloads. There are six different types of Azure VM, each designed to run different workloads.

• General purpose: This VM type is designed for a balanced ratio of CPU to memory. These are good options for workloads that need to support low to medium web servers. The basic tier within this family is best for development and test scenarios that don’t require advanced functionality, like load balancing and auto scaling.
• Compute optimized: This type has a high CPU-to-memory ratio and is optimized for CPU-intensive workloads. It is good for medium traffic web servers, network appliances, batch processes, and application servers. The Azure VM sizes within this group include the Fs and F series.
• Memory optimized: This VM type provides a high memory-to-CPU ratio and works well with production workloads, such as database servers and in-memory caches, which require a lot of memory. Memory-optimized Azure VM sizes include the Esv3, Ev3, M, GS, G, DSv2, DS, Dv2, and D series VMs. The M-Series VM size offers up to 128 vCPUs and 2 TB of total memory.
• Storage optimized: For workloads that require heavy read/write operations and low latency performance, such as big data, the Ls series is a good fit. There are four Azure VM sizes in the Ls series, ranging from hundreds to thousands of gibibytes (GiB) of local solid-state drive (SSD)-backed storage, offering fast read/write performance.
• GPU: The NV and NC VM sizes in this group are for heavy graphic-rendering workloads and video editing. These Azure VM sizes are powered by Nvidia GPUs.
• High performance compute: These compute-intensive VMs include the H and A8-11 series. The underlying hardware that powers these VMs are optimized for compute- and network-intensive workloads, including high-performance computing cluster applications.

There are several variations within a particular VM type, which can make it difficult to choose the right size. Once you choose the type of VM you need for that workload, then you can focus on evaluating the specific series type and VM size.

How to choose the right VM series in Azure?

Once, you have chosen a VM type, it is time to narrow it down to the series that you want. There are a large number of series available on Microsoft Azure. The most common ones are-

• A Series VM: Generally seen in small and medium businesses and are used in entry level workloads like development and test machines. A series VMs are economical and useful in situations where cost-efficiency is a priority.
• B Series VM: They are economical with low CPU utilization. However, if you need it, the utilization can be boosted to handle the requirements. They are typically used as small databases and build servers.
• D Series VM: Designed to run applications with high compute power and temporary disk and memory performance. D-Series VMs give faster processors, high memory to core ratio and Solid State Drive(SSD) for temporary disks. They work well with enterprise applications, relational databases and analytics.
• Dv3 & Dv2 Series VM: These types of VMs are similar to D-series, but with more powerful CPUs. The Dv2 Series CPU is 35% faster than D-series CPU. Dv2 series is based on the latest generation 2.4GHz Intel Xeon® E5-2673 v3 (Haswell) processor with Intel Turbo Boost Technology 2.0 and can go up to 3.1GHz. The memory capacity and disk configurations are the same as the D2 series.
• F Series VM: Optimized for intensive workloads and provide higher CPU to memory ratio, 2GB Ram and 16GB Solid State Drive (SSD) per CPU core. Based on the 2.4 GHz Intel Xeon® E5-2673 v3 (Haswell) processor, these VMs can achieve clock speeds as high as 3.1 GHz with the Intel Turbo Boost Technology 2.0. F Series VMs are used in web servers, batch processes, and gaming.
• G Series VM: These VMs run on hosts that have Intel Xeon E5 V3 processor with features up to half a TB RAM and 32 CPU cores that will be useful in handling heavy requirements like data warehousing and large databases.
• H Series VM: They are high performance computing Virtual Machines. H series VMs are built on Intel Haswell processor technology, specifically E5-2667 V3 processors with 8 and 16 core VM sizes, both featuring DDR4 memory and local SSD based storage.
• L Series VM: Storage optimized Virtual Machines that are built on Intel Haswell processor technology, specifically E5 Xeon v3 processors with 4, 8, 16 and 32 core VM sizes. L series supports up to 6TB local SSD and provides unmatched storage I/O performance.
• M Series VM: The largest memory-optimized Virtual machines. M series Virtual Machines are ideal for heavy in-memory workloads such as SAP HANA. The M series offers the largest memory capacities starting from 1 TiB RAM on a single VM, and the VMs offer the highest virtual CPUs up to 128 vCPUs on a single Virtual Machine.
• N Series VM: GPU (Graphic Processing Unit) enabled Virtual Machines. The N-series features the NVIDIA Tesla accelerated platform as well as NVIDIA GRID 2.0 technology, providing the highest-end graphics support available in the cloud today. One of the N-series VMs has a second low latency, high-throughput network interface (RDMA) tuned for tightly coupled, parallel computing workloads.

Evaluating Azure VM performane

After getting an idea about what kind of VM series you would need, you can evaluate it’s performance using the Azure Compute Unit (ACU). ACU rating could help you finalize your decision. The ACU metric provides a quick way of gauging the relative performance of different virtual machine sizes without knowing the underlying hardware details. It is based on the A0 (extra small) having a value of 50. A VM with an ACU of 100 has twice the compute of a VM with an ACU of 50. A VM with an ACU of 200 would be twice that of a VM with an ACU of 100 and so on.

Sizing guidance with Azure

If you are still unsure about the VM size that is right for you, Microsoft Azure offers sizing guidance with its Azure Migrate service. This is provided to make the transition to cloud easier for users. The service helps you decide which of your existing on-premises workloads are suitable for Azure. It also offers sizing recommendations and estimated monthly costs.

Choosing the right VM type and size can make or break the running of your application. The best part about Microsoft Azure is that you can change the sizing requirements according to your needs and requirements. If you need any help with cloud migration, reach out to us to schedule a no-obligation consultation.