Feature Descriptions for Linux and FreeBSD virtual machines on Hyper-V
Updated: December 12, 2014
Applies To: Hyper-V Server 2012, Windows 8.1, Windows Server 2008 R2, Windows Server 2012 R2, Microsoft Hyper-V Server Technical Preview, Windows Server 2012, Hyper-V Server 2012 R2, Windows 10 Technical Preview, Windows Server Technical Preview, Windows 8
The following features are described in this section:
With this feature, an administrator can shut down virtual machines from the Hyper-V Manager. For more information, see Operating system shutdown.
This feature ensures that the maintained time inside a virtual machine is kept synchronized with the maintained time on the host. For more information, see Time synchronization.
With this feature, a virtual machine can use multiple processors on the host by configuring multiple virtual CPUs.
With this feature, the host to can track the state of the virtual machine. For more information, see Heartbeat.
Integrated mouse support
With this feature, you can use a mouse on a virtual machine's desktop and also use the mouse seamlessly between the Windows Server desktop and the Hyper-V console for the virtual machine.
Hyper-V-specific Storage device
This feature grants high-performance access to storage devices that are attached to a virtual machine.
Hyper-v specific Network device
This feature grants high-performance access to network adapters that are attached to a virtual machine.
With this feature, an administrator can increase the size of network frames beyond 1500 bytes, which leads to a significant increase in network performance.
VLAN tagging and trunking
With this feature, you can configure virtual LAN (VLAN) traffic for virtual machines.
With this feature, you can migrate a virtual machine from one host to another host. For more information, see Virtual Machine Live Migration Overview.
Static IP Injection
With this feature, you can replicate the static IP address of a virtual machine after it has been failed over to its replica on a different host. Such IP replication ensures that network workloads continue to work seamlessly after a failover event.
vRSS (Virtual Receive Side Scaling)
Spreads the load from a virtual network adapter across multiple virtual processors in a virtual machine. For more information, see Virtual Receive-side Scaling in Windows Server 2012 R2.
TCP Segmentation and Checksum Offloads
Transfers segmentation and checksum work from the guest CPU to the host virtual switch or network adapter during network data transfers.
With this feature, an administrator can resize a fixed-size .vhdx file that is attached to a virtual machine. For more information, see Online Virtual Hard Disk Resizing Overview.
Virtual Fibre Channel
With this feature, virtual machines can recognize a fiber channel device and mount it natively. For more information, see Hyper-V Virtual Fibre Channel Overview.
Live virtual machine backup
This feature facilitates zero down time backup of live virtual machines.
Note that the backup operation does not succeed if the virtual machine has virtual hard disks (VHDs) that are hosted on remote storage such as a Server Message Block (SMB) share or an iSCSI volume. Additionally, ensure that the backup target does not reside on the same volume as the volume that you back up.
TRIM hints notify the drive that certain sectors that were previously allocated are no longer required by the app and can be purged. This process is typically used when an app makes large space allocations via a file and then self-manages the allocations to the file, for example, to virtual hard disk files.
Configuration of MMIO gap
With this feature, appliance manufacturers can configure the location of the Memory Mapped I/O (MMIO) gap. The MMIO gap is typically used to divide the available physical memory between an appliance's Just Enough Operating Systems (JeOS) and the actual software infrastructure that powers the appliance.
Dynamic Memory – Hot Add
With this feature, you can dynamically increase the amount of memory that is available to a live virtual machine. To provision a virtual machine with dynamic memory, the administrator must specify three parameters:
Startup memory, Minimum memory, and Maximum memory.
When the virtual machine is first started, the available memory is equal to the Startup memory. As the memory requirements within the virtual machine increase due to application workloads, Hyper-V dynamically provides more memory via its Hot-Add mechanism.
The maximum amount of memory that can be made available to the virtual machine is capped by the value of the Maximum memory parameter.
For more information, see Hyper-V Dynamic Memory Overview
Dynamic Memory – Ballooning
This feature dynamically provisions and deprovisions the amount of memory that is allocated to a live virtual machine.
If a virtual machine is configured with dynamic memory, Hyper-V continuously monitors memory requirements within the virtual machine. If the required amount of memory falls below the amount of memory that is allocated, then Hyper-V can automatically deprovision memory from the virtual machine. Similarly, if memory requirements increase, Hyper-V dynamically provisions more memory to the virtual machine.
Note that if the amount of allocated memory falls to the Minimum memory parameter that is specified for the virtual machine, Hyper-V abstains from further deprovisioning.
Also note that this feature is different from Hot Add. Hot Add increases the amount of memory available (or visible) to a virtual machine. Ballooning adjusts the actual amount of memory allocated to a virtual machine. The allocated memory can take up any value between the specified Minimum memory and the total available memory.
Hyper-V-specific video device
This feature provides high-performance graphics and superior resolution for virtual machines.
KVP (Key-Value pair) exchange
This feature provides a key/value pair (KVP) exchange service for virtual machines. Typically administrators use the KVP mechanism to perform read and write custom data operations on a virtual machine. For more information, see Data Exchange: Using key-value pairs to share information between the host and guest on Hyper-V.
With this feature, an administrator can issue Non-Maskable Interrupts (NMI) to a virtual machine. NMIs are useful in obtaining crash dumps of operating systems that have become unresponsive due to application bugs. These crash dumps can be diagnosed after you restart.
PAE Kernel Support
Physical Address Extension (PAE) technology allows a 32-bit kernel to access a physical address space that is larger than 4GB.Older Linux distributions such as RHEL 5.x used to ship a separate kernel that was PAE enabled. Newer distributions such as RHEL 6.x have prebuilt PAE support.
File copy from host to guest
This feature allows files to be copied from the host physical computer to the guest virtual machines without using the network adaptor. For more information, see Guest services.
Boot using UEFI
This feature allows virtual machines to boot using Unified Extensible Firmware Interface (UEFI).
For more information, see Generation 2 Virtual Machine Overview.
This feature allows virtual machines to use UEFI based secure boot mode. When a virtual machine is booted in secure mode, various operating system components are verified using signatures present in the UEFI data store.
For more information, see Secure Boot.