What is the maximum supported configuration for Hyper-V VMs?
Microsoft focused on developing Hyper-V to further extend its maximum supported configurations in Windows Server 2012. The latest version supports more memory and virtual processors, and has new features to compete with leading virtualization vendors, such as VMware. This all means Microsoft Hyper-V virtual machines (VMs) in Windows Server 2012 are more scalable than in previous versions.
Memory: Hyper-V virtual machines can be configured with a maximum of 1 TB of memory. It is important to note that Hyper-V hosts must have more than 1 TB of RAM available before the VMs can be configured. Since Windows Server 2012 hosts support up to 4 TB of memory, it is now possible to configure VMs with 1 TB of RAM.
Virtual processors: Hyper-V allows you to configure a maximum of 64 virtual processors (vCPUs) for a VM. Windows Server 2012 and 2012 R2 hosts support 2,048 vCPUs.
Maximum hard-disk size: For Hyper-V VMs using VHD files, a maximum of 2,048 GB can be created, which is what Windows Server 2008 R2 had offered. The new VHDX format, available in Windows Server 2012 and 2012 R2, supports a maximum of 64 TB.
Maximum number of active VMs: Windows Server 2012 and 2012 R2 Hyper-V allows you to configure and run a maximum of 1024 VMs, provided there are enough resources available on the Hyper-V host to support them.
Number of VMs in a cluster: You can configure a maximum of 8,000 VMs as cluster resources in a Hyper-V cluster running on Windows Server 2012 and 2012 R2.
Virtual disk controllers: Hyper-V has been supporting IDE and SCSI controllers since its first release. Starting with Windows Server 2012, Hyper-V can also support virtual host bus adapter (HBA) controllers. A maximum of two IDE controllers can be added and a maximum of four disks can be attached to these IDE controllers. There are four SCSI controllers available for you to use with a single VM, and each SCSI controller can support up to 64 disks. So, a maximum of 256 disks are supported on SCSI controllers. For virtual HBAs, a maximum of four virtual HBA controllers can be added to a VM. IDE controllers are always used to boot VMs, but starting with Windows Server 2012 R2, a VM can also boot off a SCSI controller with Generation 2 VMs.
Online resizing of virtual hard disks: There is no need for downtime when resizing a Hyper-V VM's virtual hard disks. Windows Server 2012 R2 provides support for expanding and shrinking VHDX disks that are connected to a SCSI controller.
Windows Server 2012 R2 Hyper-V features: Generation 2 virtual machines
Guidelines for moving multiple VMs with Hyper-V Live Storage Migration
Dig Deeper on Virtual machine provisioning and configuration
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