Overview

Microsoft SQL Server is unusual in having two licensing models. Having two licensing models can sometimes cause confusion.

I will cover these two license models. My aim is to make the information clear and concise.

I will first cover the licensing model known as the Server + CAL licensing model.

Then I will cover the licensing model known as the Per Core licensing model.

Table of SQL Server licensing models

How to license a SQL server using the Server + CAL licensing model

The licensing models for SQL Standard

SQL Server 2019 Standard is available in both licensing models:

(i) Server + CAL licensing model.

(ii) Per Core licensing model.

However, SQL Server 2019 Enterprise is only available in the Per Core licensing model.

About the Server + CAL licensing model

The Server + CAL licensing model only applies to the SQL Server Standard Edition.

In order to license SQL Server Standard Edition software under the Server + CAL licensing model you need to purchase:

(i) a server license for each operating system environment [physical server or virtual machines (VMs)] and

(ii) a client access license (CAL) for each user (User CAL) and/or device (Device CAL) that will access the SQL server or any of its components.

A Device CAL is required for every device not operated by humans.

For human operated devices, such as PCs, mobile phones, hand-held terminals, User CALs or a Device CALs can be used.

A single CAL permits access to any number of licensed SQL servers.

SQL Server CALs are required for all users or devices that input data into, query, or view data from a SQL Server database either directly or indirectly (through a pooling device, an intermediary system or product, a web-based application, etc.). Such technique of aggregating or pooling connections to a SQL server is defined as “multiplexing”.

Products

SQL 2019 Standard Server: Microsoft SQL Server 2019 Standard - Perpetual Server License and Server Software Package

SQL Device CALs: https://www.tekgiasoftware.com/software-for-business/313-microsoft-sql-server-2019-device-cal.html

SQL User CALs: https://www.tekgiasoftware.com/software-for-business/314-microsoft-sql-server-2019-user-cal.html

How to license a SQL server under the Per Core licensing model

The licensing models for SQL Standard and SQL Enterprise

SQL Server 2019 Standard is available in both licensing models:

(i) Server + CAL licensing model.

(ii) Per Core licensing model.

SQL Server 2019 Enterprise is only available in the Per Core licensing model.

About the Per Core licensing model

Under the Per Core licensing model, each server running SQL Server or any of its components must be assigned an appropriate number of SQL Server 2019 core licenses.

The number of required core licenses depends on whether customers are licensing a physical server or individual virtual operating system environments (OSEs).

OSE is defined as an operating system (OS) instance installed either on a physical server or on a virtual machine.

To license SQL Server Enterprise or Standard running in a physical OSE, all physical cores on the server must be licensed with the respective SQL Server 2019 licenses.

A minimum of four core licenses is required for each physical processor on the server.

Core licenses are sold in packs of two. In other words, one SKU (called a 2 Core Pack) contains two core licenses.

For example:

    • a server with two 8-core CPUs needs 2 x 8 = 16 core licenses or 8 two-core license packs;
    • a server with one CPU with two cores (if you can find one) requires 4 core licenses to satisfy the requirement of a minimum of four core licenses per processor.

There are two options for licensing SQL Server in a virtualized environment under the Per Core licensing model:

    • to license individual virtual machines (VMs);
    • to license the entire physical server with the SQL Server Enterprise Edition.

In order to license an individual VM (virtual OSE) for SQL Server Enterprise or SQL Server Standard, all virtual cores (v-cores, virtual processors, virtual CPUs) allocated to the VM must be licensed with the corresponding SQL Server 2019 licenses, subject to a minimum four-core license per VM. For example:

    • a VM configured with 6 vCPU requires 6 core licenses or 3 two-core license packs;
    • a VM configured with 2 vCPU requires 4 core licenses to satisfy the requirement of a minimum of four core licenses per VM.

If all physical cores on a server are licensed with the SQL Server Enterprise Edition, customers can run SQL Server software in a number of OSEs (physical and/or virtual) equal to the number of core licenses assigned to the server. In such configuration there are no restrictions on the number of vCPUs that can be allocated to each OSE.

Additional core licenses can be assigned to a fully licensed server to increase the maximum number of VMs permitted to run SQL Server software. Each additional core license allows deployment of SQL Server software in one additional VM.

Maximum virtualization can be achieved via the Software Assurance Unlimited Virtualization benefit. Customers are permitted to run any number of instances of SQL Server 2019 Enterprise Edition software in an unlimited number of VMs on a server with all physical cores fully licensed with SQL Server Enterprise Edition and covered by Software Assurance.

Products

SQL Server 2019 Standard 2 Core perpetual: Microsoft SQL Server 2019 Standard 2 Core Perpetual

SQL Server 2019 Standard 2 Core subscription: Microsoft SQL Server 2019 Standard 2 Core Subscription