I have been reading a few of the latest Ebooks from Microsoft press lately:
In this book, I felt it gave one of the better summaries of the new changes with Hyper-V and I am just copying a section from them as seen below.
“One of the key ways that Windows Server 2012 R2 advances the Hyper-V virtualization platform is in its support for a new generation of virtual machines. Microsoft refers to these as “Generation 2″ virtual machines, and they have the key following characteristics:
UEFI-based
Beginning with Windows 8 and Windows Server 2012, Microsoft Windows now supports the Secure Boot feature of the Unified Extensible Firmware Interface (UEFI). This means that UEFI is now part of the Windows 8 and Windows Server 2012 boot architecture, and it replaces the Basic Input/ Output System (BIOS) firmware interface used by previous versions of Windows for initiating the boot process. Generation 2 virtual machines comply with the UEFI Secure Boot standard and enable virtual machines to use Secure Boot.
Legacy free
In previous versions of Hyper-V, virtual machines used a standard set of emulated hardware devices to ensure compatibility running all versions of Windows. These emulated devices include an AMI BIOS, Intel 440BX chipset motherboard, S3 Trio graphics display adapter, Intel/ DEC 21140 network adapter, and so on. With Generation 2 virtual machines, many of these emulated devices have now been removed and replaced with synthetic drivers and software-based devices.
SCSI boot
Virtual machines in previous versions of Hyper-V needed to boot from integrated development environment (IDE) disks (virtual disks attached to the virtual machine using the IDE controller). Beginning with Windows Server 2012 R2, however, Generation 2 virtual machines can now boot directly from SCSI disks (virtual disks attached to the virtual machine using the SCSI controller). In fact, Generation 2 virtual machines don’t even have an IDE controller! Generation 2 virtual machines can also boot from a SCSI virtual DVD.
Faster deployment
Network-based installation of a guest operating system onto a Generation 2 virtual machine is significantly faster than for the previous generation of Hyper-V virtual machines for two reasons. First, the Legacy Network Adapter device is no longer required (or even supported) by Generation 2 virtual machines. Instead, you can PXE-boot a Generation 2 virtual machine using a standard network adapter. Second, the SCSI controller performs much better than the legacy IDE controller in the previous generation of virtual machines. The result is that installing a supported guest operating system in a Generation 2 virtual machine takes only about half the time as installing the same guest operating system in a previous generation virtual machine.”
- Copied from: Tulloch, Mitch (2013-10-30). Introducing Windows Server 2012 R2 (Kindle Location 281). Microsoft Press. Kindle Edition.
Introducing Windows Server 2012 R2