The Hyper-V role in Windows Server 2008 R2 provides you with the tools and services you can use to create a virtualized server computing environment. This virtualized environment can be used to address a variety of business goals aimed at improving efficiency and reducing costs. This type of environment is useful because you can create and manage virtual machines, which allows you to run multiple operating systems on one physical computer and isolate the operating systems from each other.
According the the release notes of Microsoft Windows Server 2008 R2, the Hyper-V role now fully supports Live Migration of Virtual Machines using the failover clustering role, added and configured on the servers running Hyper-V.
Live migration allows you to transparently move running virtual machines from one node of the failover cluster to another node in the same cluster without a dropped network connection or perceived downtime. Live migration requires the failover clustering role to be added and configured on the servers running Hyper-V. In addition, failover clustering requires shared storage for the cluster nodes. This can include an iSCSI or Fiber-Channel Storage Area Network (SAN). All virtual machines are stored in the shared storage area, and the running virtual machine state is managed by one of the nodes.
On a given server running Hyper-V, only one live migration (to or from the server) can be in progress at a given time. This means that you cannot use live migration to move multiple virtual machines simultaneously.
We recommend using the new Cluster Shared Volumes (CSV) feature of Failover Clustering in Windows Server 2008 R2 with live migration. CSV provides increased reliability when used with live migration and virtual machines, and also provides a single, consistent file namespace so that all servers running Windows Server 2008 R2 see the same storage.
Why is this change important?
Live migration does the following to facilitate greater flexibility and value:
- Provides better agility. Datacenters with multiple servers running Hyper-V can move running virtual machines to the best physical computer for performance, scaling, or optimal consolidation without affecting users.
- Reduces costs. Datacenters with multiple servers running Hyper-V can service their servers without causing virtual machine downtime or the need to schedule a maintenance window. Datacenters will also be able to reduce power consumption by dynamically increasing consolidation ratios and turning off unused servers during times of lower demand.
- Increases productivity. It is possible to keep virtual machines online, even during maintenance, which increases productivity for both users and server administrators.