It has been almost one year since Windows Server 2016 was released at Microsoft Ignite. Are the virtual machine sizing recommendations for Windows Server 2012R2 applicable to Windows Server 2016? And since we are talking about sizing virtual machines for XenApp and XenDesktop, it might be a good time to revisit Windows 10.

Let’s first look at virtual CPU allocation recommendations:

User Workload	Operating System	vCPU Configured for Scale	vCPU Configured for Experience
Light	Windows 7	2 vCPU	2 vCPU
	Windows 10	2 vCPU	2 vCPU
	Windows 2012R2	NUMA or ½ of NUMA	NUMA or ½ of NUMA
	Windows 2016	NUMA or ½ of NUMA	NUMA or ½ of NUMA
Medium	Windows 7	2 vCPU	3 vCPU
	Windows 10	2 vCPU	3 vCPU
	Windows 2012R2	NUMA or ½ of NUMA	NUMA or ½ of NUMA
	Windows 2016	NUMA or ½ of NUMA	NUMA or ½ of NUMA
Heavy	Windows 7	3 vCPU	4 vCPU
	Windows 10	3 vCPU	4 vCPU
	Windows 2012R2	NUMA or ½ of NUMA	NUMA or ½ of NUMA
	Windows 2016	NUMA or ½ of NUMA	NUMA or ½ of NUMA

Windows Server

Even though Windows 2016 is more CPU intensive than Windows 2012R2, that does not change how we allocate virtual CPUs to our Windows 2016 virtual machines. We want to align our vCPU allocation with the NUMA configuration of our physical processor. This alignment results in us either making our vCPU allocation equal to NUMA or half of NUMA, but when we use half of NUMA, we need to double the number of virtual machine instances.

Windows Desktop

For Windows 10 we simply align our vCPU allocation with the user workload and our configuration goals. If we want to give the users the best overall experience, we want to allocate extra vCPU resources, but this will increase costs as we might over allocate resources. Using “configured for scale” as our plan will give the users a good experience, but, depending on the applications, might become sluggish if under extreme load.

After vCPU, many architects want to start estimating RAM requirements.

User Workload	Operating System	vRAM Configured for Scale	vRAM Configured for Experience
Light	Windows 7	2 GB	3 GB
	Windows 10	2 GB	3 GB
	Windows 2012R2	256 MB per user	256 MB per user
	Windows 2016	320 MB per user	320 MB per user
Medium	Windows 7	3 GB	4 GB
	Windows 10	3 GB	4 GB
	Windows 2012R2	512 MB per user	512 MB per user
	Windows 2016	640 MB per user	640 MB per user
Heavy	Windows 7	6 GB	8 GB
	Windows 10	6 GB	8 GB
	Windows 2012R2	1024 MB per user	1024 MB per user
	Windows 2016	1280 MB per user	1280 MB per user

Windows Server

RAM allocation between Windows Server 2012R2 and Windows Server 2016 is slightly different. Based on performance tests, Windows Server 2016 utilizes more RAM than Windows Server 2012R2. Windows Server 2016 includes more capabilities than Windows Server 2012R2 so an increase in RAM utilization is expected, but these can be slightly offset with proper Windows 2016 optimization.

Windows Desktop

Just like vCPU, RAM allocation for Windows desktops is fairly straight forward. Out of the box, Windows 10 consumes more RAM than Windows 7, but with proper optimization (default apps, scheduled tasks, services and runtime), it is possible to reduce overall RAM consumption on Windows 10.

Of course, all of these numbers are based on your application workload, but the expectation is that the heavier the workload, the more RAM users require.

Daniel (Follow on Twitter @djfeller)
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