Once you have the network, location, name, and purchase model decided, it’s time to decide the size of the VM. In Azure, VMs come in different sizes with a predefined set of CPU, memory, and storage capacities.
The OS disk capacity and the temp disk capacity will be decided by the size. You don’t have to define these values independently; rather, choose the appropriate size. These sizes have been categorized into different VM families based on the underlying hardware used. The key factor behind choosing the size is the type of workload you are running on the VM. Table 7.1 lists the available VM sizes at the time of writing this book. Please note that Microsoft is constantly adding new VM sequences to the list, and it is always recommended that you refer to the Microsoft documentation for size planning and newer sizes.
TABLE 7.1 VM Types and Sizes
| Type | Sizes | Description |
| General purpose | B, Dsv3, Dv3, Dasv4, Dav4, DSv2, Dv2, Av2, DC, DCv2, Dv4, Dsv4, Ddv4, Ddsv4 | Balanced CPU to memory ratio. Used for testing, development, small to medium databases, and low to medium traffic web servers. |
| Compute optimized | FSv2 | High CPU to memory ratio as this is compute optimized. Ideal for medium traffic web servers, network appliances, parallel processing, and application servers. |
| Memory optimized | Esv3, Ev3, Easv4, Eav4, Ev4, Esv4, Edv4, Edsv4, Mv2, M, DSv2, Dv2 | High memory to CPU ratio as this is memory optimized. Great choice for medium to large cache and databases. |
| Storage optimized | Lsv2 | Offers high disk throughput and I/O, making it ideal for big data, SQL, NoSQL, and data warehousing. |
| GPU | NC, NCv2, NCv3, ND, NDv2, NV, NVv3, NVv4 | Offers single and multiple GPUs. Ideal for graphic-intensive workloads such as video rendering and model training. |
| HPC | HB, HBv2, HC, H | High-performance computing offers powerful and fastest CPU with optional high throughput network interfaces. |
| Confidential compute | DCsv2 | Supports a larger range of deployment capabilities, has 2x the Enclave Page Cache (EPC), and has a larger selection of sizes compared to the DC-Series VMs. |
Azure also allows you to change the size of the virtual machines per your business requirements. This process is called VM resizing, and you can resize to any supported size. During the resize, the VM will reboot. Hence, it is recommended that you schedule a maintenance window while resizing critical workloads.