Server 2008 Hyper-V solution.
Supported VSS (Volume Shadow copy Service) live backup of virtual machines.
This allowed a backup to be taken of a virtual machine from the host operating
system. The VSS request for the backup was then communicated to the virtual
machine’s guest operating system through the Hyper-V Integration Services to
ensure that the application data in the VM was in an application-consistent state
and suitable for a backup.
The ability to create VM snapshots, which are point-in-time captures of a virtual
machine’s complete state (including memory and disk). This allowed a VM to be
rolled back to any of these snapshots. The use of the term snapshots was
confusing, because the term is also used in the backup VSS nomenclature, but in
this case it’s referring to snapshots used in the backup process, which are different
from VM snapshots. In Windows Server 2012 R2, VM snapshots are now called
checkpoints to help remove this confusion.
Pass-through disk access for VMs was possible even though not generally
recommended. It was sometimes required if VMs needed access to single volumes
greater than 2TB in size (which was the VHD limit).
Integration services available for supported guest operating systems, allowing
capabilities such as heartbeat, mouse/keyboard interaction, backup services, time
synchronization, and shutdown
Multiple virtual networks could be created with support for 10Gbps and VLANs.Windows Server 2008 R2 Changes
While Windows Server 2008 Hyper-V offered a solid foundation and a reliable
solution for a v1, several limitations stopped Hyper-V from being seriously considered
in many environments, among them the ability to move virtual machines between
hosts in a cluster with no downtime. There were two challenges for Hyper-V to enable
this:
The VM had to be paused to enable the memory, processor, and device state to be
saved to disk.
NTFS is not a shared filesystem and can be mounted by only one OS at a time,
which means that when a virtual machine moves between hosts in a cluster, the
logical unit number, or LUN (which is a block of storage from a SAN), must be
dismounted from the source host and mounted on the target host. This takes time.Windows Server 2008 R2 solved both of these challenges. First, a new technology
called Live Migration was introduced. Live Migration enabled the memory of a virtual
machine and the virtual machine’s state to be replicated to another host while the
virtual machine was still running and then switched over to the new host with no
downtime. I cover this in detail in Chapter 7, “Failover Clustering and Migration
Technologies,” but the technology worked at a high level using the following steps: