Evaluate This–High Availability Virtual Machines

Server virtualisation is all about decoupling the operating system form the hardware it’s running on, and one of the benefits of doing this is to ensure that a virtual machine (VM) can be made resilient to any underlying hardware failure.  In the world of Hyper-V this is achieved by building a Windows Server cluster and adding the VM as a role into that cluster.  From Windows Server 208 R2 this also gives the benefit of moving the virtual machine around  nodes on the cluster without stopping the virtual machine (known as live migration).

In Windows Server 2012 you still need to use a cluster to make virtual machines highly available, but you also have the option to build a cluster without any shared storage using a file share to host the virtual machines storage and metadata.  This screencast shows how that works..

Things to note.

This builds on two other posts in this series:

What I have done here illustrates the technology for high availability in Windows Server 2012  and is not a high availability solution itself – the high availability file server is running on two virtual machines but these are connecting to an iscsi target that isn’t highly available itself and I have no redundant network infrastructure.

As with several of my screencasts it’s a SQL Server 2012 VM that's is being migrated around.  I run my Resource Governor demo application on the VM while it’s being migrated as this enables me to max out the CPU on the VM to show that migration doesn’t significantly slow this process and certainly doesn’t stop it.  I also use remote desktop to connect to the VM because if I used the VM console it would drop during migration because the console is connecting to the VM via the host and of course the host changes during the migration.

To try this yourselves you’re going to need at least two physical hosts (laptops/servers etc.) as well as Windows Server 2012.