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Microsoft has long offered a free version of Hyper-V Server, but, for whatever reason, Hyper-V Server has gained a reputation for only being appropriate for use in a lab environment. Believe it or not, it is possible to deploy the free Hyper-V Server in a way that allows your Hyper-V virtual machines to be made highly available.
In order to build a fault-tolerant Hyper-V deployment, there are a few things that you'll need. First, you will need a storage array that can be used for shared storage. These storage requirements are the same as for any other Hyper-V deployment. Next, you need a copy of Hyper-V Server, which can be found on the Microsoft website.
Third, you require a basic understanding of how failover clustering is normally deployed and configured. Having some up-front knowledge of failover clustering will make it much easier to build a cluster based on Hyper-V Server.
Finally, to build a fault-tolerant Hyper-V deployment, you must have a general knowledge of PowerShell. If your PowerShell comprehension is a little rusty, I recommend taking advantage of the Sconfig.cmd utility. This utility provides a menu-driven interface for configuring a server. Employing this utility will minimize the amount of PowerShell that you will have to use.
Putting the pieces together
The first step in building a failover cluster using the free Hyper-V Server is to install Hyper-V Server on each server that will act as a cluster node. Once it has been installed, you will need to use the Sconfig.cmd to establish the initial configuration for each server. This means assigning an IP address to each network interface card (NIC), giving each node a unique and meaningful computer name, joining an Active Directory domain, and enabling remote management. All of these tasks can be easily completed using the Sconfig.cmd utility.
Once you complete the initial configuration process, you must make a few decisions regarding your failover cluster. You will need to choose a name and an IP address for the cluster. You will also need to figure out how you are going to connect the cluster nodes to the shared storage. The easiest solution is to create two Server Message Block file shares. One of these shares will be used as shared storage, while another is used as a File Share Witness.
Commands to build the cluster
For the sake of demonstration, let's pretend that you wanted to create a cluster with a cluster name of "Cluster1" and a cluster IP address of 192.168.0.1. Let's also assume that the NIC that you want to use for cluster communications on each cluster node is named "Ethernet 2" -- you can get the actual NIC name by using the Get-NetAdapter cmdlet. Now imagine that your cluster nodes are named "Hyper-V-1," "Hyper-V-2" and "Hyper-V-3". Finally, we will need a Universal Naming Convention path for our File Share Witness. We will also need to assign a name to the Hyper-V virtual switch. For the sake of this demonstration, I will use "Switch1" as the virtual switch name -- each node must use the same virtual switch name -- and I will use "\\storage\witness" as the File Share Witness path. Given those conventions, the commands used to build a failover cluster would be:
Install-WindowsFeature –Name Failover-Clustering –IncludeManagementTools
New-VMSwitch "Switch1" –NetAdapterName "Ethernet 2" –AllowManagementOS:$True
Test-Cluster –Node Hyper-V-1,Hyper-V-2,Hyper-V-3
New-Cluster –Name Cluster1 –Node Hyper-V-1,Hyper-V-2,Hyper-V-3 –StaticAddress 192.168.0.1
Set-ClusterQuorum –Cluster Cluster1 –NodeAndFileShareMajority \\Storage\Witness
The only thing left to do at this point is to connect your shared storage to the cluster. The method that you will use to do so will vary depending on the type of storage that you are using. You can use the Add-ClusterDisk cmdlet to get the job done, but I advise installing the Failover Cluster Manager onto another Windows Server, one that has a graphical user interface, and use that tool to add storage to the cluster. That way you won't have to worry about the complexities of configuring shared storage from the command line.
As you can see, it is possible to achieve high availability using the free Hyper-V Server. That being the case, you may be wondering why any organization would pay for a Windows Server license for their Hyper-V nodes. The answer usually comes down to VM licensing. Windows Server 2012 R2 Datacenter Edition for instance allows a properly licensed Hyper-V host to run an unlimited number of Windows Server 2012 R2 VMs. Without such a license, VM licensing must be handled separately, which can be costly and complicated.
Drawbacks to the free Hyper-V Server
Choosing the right Hyper-V PowerShell cmdlet
The high cost of Windows Server licensing
Microsoft makes Windows failover cluster upgrade process easier