Microsoft Windows Server 2012 R2 includes two generations of virtual machine configurations: Generation 1 and Generation 2. It is a version of the Windows Server operating system.
Generation 1 virtual machines are the traditional virtual machines available in previous versions of Hyper-V. They use a BIOS-based virtual hardware platform and can boot from virtual hard disks or virtual DVD drives. They support legacy devices like emulated network adapters, SCSI controllers, and IDE controllers.
On the other hand, Generation 2 virtual machines use the UEFI-based virtual hardware platform and are only available on 64-bit editions of Windows Server 2012 R2 or later. Virtual SCSI and DVD drives can be used to boot, and synthetic devices, such as a network adapter, storage controller, and mouse, are also supported.
The main differences between Generation 1 and Generation 2 virtual machines are:
1. Boot process: Generation 1 virtual machines boot using BIOS firmware, while Generation 2 virtual machines boot using UEFI firmware. UEFI provides faster boot times and improved security.
2. Device support: The virtual machines of Generation 2 have synthetic devices that are optimized for virtualization and provide better performance and scalability. They do not support legacy devices like emulated network adapters, SCSI controllers, and IDE controllers.
3. Compatibility: Virtual machines of Generation 1 are compatible with most guest operating systems, including legacy operating systems that do not support UEFI firmware. As the host operating system, Generation 2 virtual machines require Windows Server 2012 R2 or later and can only run 64-bit guest operating systems that support UEFI.
In summary, while Generation 1 and Generation 2 virtual machines are supported in Windows Server 2012 R2, Generation 2 offers better performance, security, and scalability features but requires a 64-bit host and guest operating systems supporting UEFI firmware.