18 C H A P T E R 2 | Compute
Figure 2-5: Entering storage account information
Note You can do the same in Windows PowerShell by using the following command:
Set-ClusterQuorum -CloudWitness -AccountName MyWitness -AccessKey -Endpoint
core.windows.net
There are two key prerequisites for using the cloud witness:
You must have a valid Azure subscription.
All nodes must have Internet access and be able to access Azure.
Additionally, as with a file-share witness, you can use the same Azure account or container for
multiple clusters.
Shared VHDX improvements
Since Windows Server 2008 Hyper-V, you have had the ability to create guest clusters as virtual
machines (VMs). However, to have any sort of shared storage, you were required to use iSCSI.
Windows Server 2012 introduced Virtual Fibre Channel support for VMs as a second option for
shared storage.
However, from the perspective of a service provider, Virtual Fibre Channel is not always a viable
option. Virtual Fibre Channel opens and provides the customer with access to the physical storage
infrastructure in the same way that physical iSCSI does. However, if a service provider set up a VM and
added iSCSI support for the customer-shared drives, the customers might be unhappy because they
would be charged for an additional VM.
Because of these concerns, Microsoft introduced Shared VHDX in Windows Server 2012 R2 as an
additional option. Shared VHDX gives guest clusters the shared storage they needed without access
to storage infrastructures. This did add another option from a shared-drive perspective; however, it
was not without limitations. In the latest Windows Server 2016 Technical Preview, improvements have
been made to address some of these limitations.
Suppose that you have a Shared VHDX drive that is filling up, and you need to increase the size. In
Windows Server 2012 R2, downtime was unavoidable because to increase the size the VMs would
need to be powered off. That is not an ideal solution for a 24/7 business. In Windows Server 2016
Technical Preview, you can now expand the drive while it is online. (Note that you can only expand a
Shared VHDX drive, you cannot shrink one.)
To expand the drive, perform the following steps:
1. Open Failover Cluster Manager, right-click a VM, and then select Settings.
2. Click the drive that you want to expand, as depicted in Figure 2-6.
