Understanding Azure VM Size Naming

Beginning with Azure VM series and sizes released since mid-2017, both new series and revisions of existing series use a naming schema that exposes information about the resource and capabilities of the specific VM size. Names start with the VM series letters, followed by the number of vCPUs within the VM size, and may be followed by additional identifiers.

A hypothetical “J16” VM size would be a J-series VM with 16 vCPUs. The following example explains a J16 VM size, J16-2mrs_v2, that has several additional features:

• J: VM series name
• 16: Number of vCPUs normally available in this size
• -2: This VM size is constrained to 2 virtual vCPUs, but retains the other resources (memory, storage) of its non-constrained peer
• m: High Memory configuration (RAM is twice that of the peer VM size)
• r: Supports RDMA high-speed networking
• s: Supports SSD-based Premium Storage
• _v2: This is the second version of this series.

Older VM series and sizes do not adhere to this schema. This includes A, D, D_v2, and G-series VMs. These series are numbered sequentially (for example, G1, G2, G3) with each subsequent size having double the CPU, RAM, and storage of the previous. For these older VM series, sizes with an “S” after the series letter, such as GS3, support SSD-based local storage.