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Nirmal is a MCSEx3, MCITP and was awarded Microsoft MVP in Directory Services. He is specialized in Directory Services, Microsoft Clustering, Hyper-V, SQL and Exchange. He has been involved in Microsoft Technologies since 1994 and followed the progression of Microsoft Operating System and software. In his spare time, he likes to help others and share some of his knowledge by writing tips and articles. Nirmal can be reached at nirmal_sharma@mvps.org.

How Scalable is Windows Server 2012 Compared to Windows Server 2008 R2?

Published 11 February 2014 7:52 pm

Every new Hyper-V release provides new features or improvements over existing features. As part of the improvement, Microsoft also keeps scalability in mind. Scalability is required by large organizations to make sure the production load can be balanced by running multiple services on the servers.

For example, you could run 512 virtual machines on a Hyper-V Server running on Windows Server 2008 R2. Similarly, you could assign 64 GB of memory to virtual machines on Hyper-V Version 2.0 running on Windows Server 2008 R2. But with Windows Server 2012, virtual machines now support up to 1 TB of memory and more as I’ll explain in this post.

This post outlines the maximum configuration supported for virtual machines running on Hyper-V and its components, Hyper-V Server and virtual networking configured on Windows Server 2008 R2 and Windows Server 2012. There are no major changes in terms of the maximum supported configuration in the upcoming Windows Server 2012 R2. So rather than comparing the Windows Server 2012’s capabilities with Windows Server 2012 R2, I would compare with Windows Server 2008 R2.

Support For Component

Maximum Configuration

In Windows Server 2012

Maximum Configuration

In Windows Server 2008 R2

Remarks

For Virtual Machine

Virtual Processor

64

4

This depends on the Guest Operating System.

For example: A guest operating system running Windows Server 2003 SP2 does not support more than 2 virtual processors. The maximum virtual processors support actually depends on the number of Physical processors configured on the Hyper-V Host. In the case of a virtual machine running on Windows Server 2008 R2, a maximum of 4 virtual processors can be configured for a Virtual Machine.

Memory

1 TB

64 GB

A Virtual Machine running on Windows Server 2012 Hyper-V can be configured with a maximum of 1 TB and 64 GB of memory is allowed for virtual machines running on Windows Server 2008 R2 Hyper-V Servers

VHD File capacity

2040 GB

2040 GB

For VHD files, the maximum supported size is 2040 GB. This applies to Fixed and Dynamic Expanding Disks Virtual Hard Disk Files. There is no change in the size of the VHD Files but a new drive type introduced (VHDX file) which has greater size and is supported on Windows Server 2012 only.

VHDX File capacity

64 TB

NA

The maximum supported size is 64 TB for VHDX files. VHDX file support was introduced in Windows Server 2012.

IDE Controllers

2

2

IDE Controller 0 is always reserved to boot the Operating System of the virtual machine. Rest IDE Controllers can be used to attach other Virtual Hard Disk files.

SCSI Controllers

4

4

Maximum 4 SCSI Controllers can be added to a Virtual Machine.

Disks Per IDE Controller

2

2

There are two IDE Controllers available with two channels. So a total of 4 Virtual Hard Disks can be attached to IDE Controllers.

Disks Per SCSI Controller

64

64

A SCSI Controller can support a maximum of 64 Virtual Hard Disks.

Total IDE Disks

4

4

A total of 4 IDE virtual hard disks can be attached to IDE Controllers.

Total SCSI Disks

256

256

A total of 256 Virtual Hard Disks can be attached to all SCSI Controllers.

Fibre Channel Adaptors

4

NA

Fibre Channel Adaptors are available only with Windows Server 2012.

Pass-Through Disk Size

Depends

Depends

Depending on the guest Operating System.

iSCSI Disks Per VM

No Limitation

No Limitation

iSCSI Disk Size

No Limitation

No Limitation

Virtual Legacy Network Adaptors

4

4

This is sometimes referred as Emulated Network Adapter.

Virtual VMBUS Network Adaptors

8

8

This is sometimes referred as Synthetic Network Adapter. VMBUS network adapters are available as part of the Integration Components.

Serial Com Ports

2

2

Snapshots per VM

50

50

There is no change in the maximum number of snapshots. It also depends on the available disk space.

For Hyper-V Servers

Logical Processors

320

64

For Windows Server 2008 R2 Hyper-V Servers, the maximum logical processor support was only 64 but it was increased in Windows Server 2012.

Number Of VMs Running

concurrently.

1024

384

You can run 1024 Virtual Machines on a Hyper-v Server running Windows Server 2012 but it also depends on the capacity of Hyper-V Server.

Virtual Processors

2048

12

A Hyper-V running on Windows Server 2012 can support up to 2048 virtual processors.

Host Memory

4 TB

1 TB

Hyper-V Host now supports 4 TB of maximum memory.

Virtual SAN

No Limitations

NA

Physical NICs

No Limitations

No Limitations

There is no limitation imposed by the Hyper-V Role.

Hyper-V Host Storage

No Limitations

No Limitations

No limits imposed by Hyper-V. It depends on the Operating System. All modern storages are supported.

NIC Teaming

No Limitations

NA

It depends on the number of Physical Network Adapters on the host machine. NIC Teaming is only supported (officially) on Windows Server 2012. There is no support provided by the Microsoft for NIC Teaming on Windows Server 2008 R2 Hyper-V Servers but you can install third-party NIC Teaming software to team physical network adapters.

Generation 2 Virtual Machines

No Limitations

NA

There is no limitation to run Generation 2 virtual machines on the Hyper-V running Windows Server 2012 R2. Generation 2 Virtual Machines are only supported on 2012 R2 Hyper-V Servers.

For Virtual Network Switches

External Virtual Switch

1 Per Physical NIC

1 Per Physical NIC

You cannot create an External Virtual Switch if there are no empty Physical Network Adapters available. You can read more about the Hyper-V Virtual Network Switches in an article published in the SysAdmin section of Simple-Talk.

Private Virtual Switch

Unlimited

Unlimited

Since a Private Virtual Switch doesn’t require a physical network adapter, you can create as many Private Virtual Switches as you need.

Internal Virtual Switch

Unlimited

Unlimited

Same as above

VMs per Switch

Unlimited

Unlimited

Since a virtual switch is a logical device, you can connect any number of virtual machines to a virtual switch.

VLAN ID on Virtual Machine

1 Per Virtual NIC

1 Per Virtual NIC

Only one VLAN ID can be assigned to a Virtual NIC. You can add 4 Legacy Network Adaptors and 8 VMBUS adaptors to a Virtual Machine. So a total of 12 VLAN IDs can be specified to a Virtual Machine.

VLAN ID on Virtual Switch

1 Per Switch

1 Per Switch

VLAN ID Tagging is only supported on Internal and External Virtual Switches. You cannot assign VLAN ID to a Private Virtual Switch.

VLAN IDs

4094

4094

There can be a maximum of 4094 VLAN IDs can be specified for virtual NICs.

For Cluster and Hyper-V

VM as Cluster Resource

8000 Per Cluster

4000 Per Cluster

A total of 8000 virtual machines can be configured in a Failover cluster, but Windows Server 2008 R2 supported only 4000 Virtual Machines per cluster.

Nodes Per Cluster

64 Nodes

16 Nodes

The Datacenter edition of Windows Server 2012 Operating System supports 64 nodes in a single cluster.

For Hyper-V Replica

Primary VMs per Primary Server

Unlimited

NA

You can configure any number of virtual machines to participate in Hyper-V Replica. This feature is available only on Windows Server 2012 and later versions.

As per the above comparison between Windows Server 2012 and Windows Server 2008 R2 Hyper-V Servers, you can see there is not much difference. However, the main difference lies between the support for virtual processors and the number of Virtual Machines can be configured in a cluster.

There are also several new Hyper-V features introduced which are only available in Windows Server 2012.

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