A condensed guide ... Microsoft Processor to Core Licensing

Gone are the more simplistic days of Microsoft Per Processor licensing when there was a basic assignment of a single license to a processor, unlimited use and access, all available across multiple editions of software. Indeed, Microsoft were touting per processor as a major point of difference looking back to even SQL Server 2008, going as far as to claim ‘thought leadership’ when it came to competitor licensing models aligned to multicore processors.

From 2016 though (and noting the GA of SQL Server 2017 from October 2017), following their conformance and gradual demise of the processor metric, there are now primarily three Per Core licensing models:

1. The Per Core model used by SQL Server and BizTalk Server;
2. The Per Core/CAL licensing model used by Windows Server (Standard and Datacenter edition) following the release of Windows Server 2016;
3. The Management Servers (core-based) licensing model used by System Center (Standard and Datacenter edition) following the release of System Center 2016.

So let’s take a look at 2 more common server products afflicted by this change, SQL Server under (1) and Windows Server under (2) – and if you are intending to use Self-Hosting or SPLA rights note that there are further considerations not covered here, the context of this blog contained to licensing acquired under Microsoft’s Volume Licensing offerings (refer: Microsoft Commercial Licensing)

SQL Server 2016
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With SQL Server 2016 Per Core licensing, each server running software or any of its components (such as Reporting Services or Integration Services) must be assigned an appropriate number of SQL Server 2016 core licenses. The number of core licenses needed depends on whether you are licensing the physical server or individual virtual operating system environments (OSEs), across either edition.

​Unlike the Server+CAL licensing model, the Per Core model allows access for an unlimited number of users or devices to connect from either inside or outside an organisation’s firewall. With the Per Core model, you do not need to purchase client access licenses (CALs) to access the SQL Server software.
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When running SQL Server in a physical OSE, all physical cores on the server must be licensed, noting software partitioning does not reduce the number of core licenses required except when licensing individual virtual machines (VMs). A minimum of four core licenses are required for each physical processor on the server,  with the use of hyper-threading not affecting the number of core licenses required when running in a physical OSE, only those licensed under individual virtual machines (which are still subject to the four core minimum).
So with the basics understood you’ll then want to familiarise with what you gain with the addition of a Software Assurance subscription…

Key SQL Server SA Benefits
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1. License Mobility: If you are deploying to a server farm with technology such as VMware’s vMotion you’ll need SA for license mobility, now extended to cloud providers that are Microsoft Authorised Mobility Partners;
2. Unlimited VMs: don’t be mistaken by the ‘Enterprise’ license denotation – without SA you can only run up a maximum number of VMs (with unlimited vCores) equal to the number of core licenses assigned to the server, and without SA that means having to buy more licenses should you exceed the maximum;
3. Failover Rights: A secondary server used for failover support does not need to be separately licensed for SQL Server as long as it is passive (ie. not serving data, such as reports to clients running active SQL Server workloads, nor performing any “work”, such as additional backups being made from secondary servers) and the primary SQL Server is covered with active SA, noting the licenses must cover the higher number of associated server cores in the HA coupling.

And be cautious – the components of a SQL Server license cannot be separated. While management tools and other software identified as additional or supplemental software such as product documentation, client connectivity tools, software add-ins, and Software Development Kits (SDKs) can generally be distributed and run on any number of devices for use with a licensed instance of SQL Server software, other licensed components such as the SQL Server Database Engine (DB), SQL Server Services for Windows, Master Data Services (MDS), Analysis Services (AS), Integration Services (IS), Reporting Services (RS), and Data Quality Services (DQS) will require licensing if deployed to other servers. You can find more details of the components at: SQL Server Software Components

And for Non-Production: Effective April 1, 2016, SQL Server Developer Edition became a free product, available for download from the Microsoft Dev Essentials program as a potential alternative to the likes of a Visual Studio subscription. SQL Server 2016 Developer Edition is a fully featured version of SQL Server software—including all of the features and capabilities of Enterprise Edition--licensed for development, test, and demonstration purposes only.

Windows Server 2016
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For both Standard and Datacenter editions, the number of core licenses required equals the number of physical cores on the licensed server, subject to a minimum of 8 core licenses per physical processor and a minimum of 16 core licenses per server (sold in 2-Core and 16-Core packs).

​Which means being very careful when you tally your overall requirement – make sure you account for the 16-Core per server minimum across any single CPU servers you might have in your inventory where you might otherwise under-allocate (where <16).

And the differences in the editions?

• Standard: When all cores on the server are licensed (subject to the minimums), you can deploy two OSEs or two Hyper-V containers and unlimited Windows Server containers.
• Datacenter: When all cores on the server are licensed (subject to the minimums) you can deploy unlimited OSEs, Hyper-V containers, and Windows Server containers.

(and if you're looking for a definition of containers, look no further - go here)

So, To Finish …

Bear in mind that in both cases you will still need to account for the CAL requirements if necessary (and remember to count all direct and indirect users/devices, ie. no multiplexing), typically via the likes of a Core CAL Suite or equivalent, which as an example provides the following licenses:
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• Windows Server CAL
• SharePoint Server Standard CAL
• Exchange Server Standard CAL
• System Center Configuration Manager Client Management License
• System Center Endpoint Protection Client Management License
• Skype for Business Server Standard CAL

​Noting that the likes of SQL Server CALs and Dynamics/CRM CALs must be acquired separately.

Microsoft have provided a very helpful Licensing Brief across Core Licensing that I would also recommend reading for more information.