Users Guide

Designing for High Availability 33
Integration between Hyper-V and Windows
Failover Clustering
As mentioned earlier, Hyper-V HA is implemented by leveraging the Windows
Failover Clustering feature in Windows Server 2008. A high level knowledge
of Failover Clustering is essential for implementing and managing a Hyper-V
Host Cluster environment. Refer to
http://www.microsoft.com/windowsserver2008/en/us/clustering-overview.aspx
for an overview of the Failover Clustering feature.
In order for Failover Clustering to manage an application as a highly available
entity, it has to manage all the dependencies for that application as well.
Failover Clustering achieves this by defining a logical entity called a Resource
Group and placing the application and its dependent resources within that
Resource Group. When a failover occurs, Failover Clustering moves all the
resources defined within a Resource Group (as a whole) across cluster nodes.
In the Failover Management console for Failover Clustering, the Resource
Group and its contents are listed under the Services & Applications section.
Failover Clustering extends this same concept to Hyper-V Host Clustering as
well. When a VM is made an HA VM, Failover Clustering creates a new
Resource Group for this VM. The logical Resource Group for an HA VM will,
at a minimum, include the following resources:
•The Virtual Machine resource defines the state of the HA VM.
•The
Virtual Machine Configuration resource maintains the HA VM’s
configuration. This resource has to be online for the VM to be available on
Hyper-V Manager .
•The
Disk Drives that host the XML, BIN, VSV, and VHD files (or
passthrough disks).
The Resource Group may include more storage disks in more complex
configurations such as when the VM has multiple disks (including
passthrough disks).
With its integration with Hyper-V, the Failover Clustering feature can
automatically identify all the dependencies for a VM and groups all the
identified resources into a single Resource Group. This activity is transparent