Leveraging Shared VHDX and VHD Sets
Windows Server 2012 R2 and above provides a feature that for most environments
will remove the need to use iSCSI inside the virtual machine or virtual Fibre Channel
and remove the need to expose the storage fabric details to the virtual machine.
Shared VHDX allows a VHDX file to be connected to multiple virtual machines
simultaneously, and the shared VHDX will be seen as shared storage (shared SAS) and
therefore used as cluster storage within guest clusters. The requirements for shared
VHDX in Windows Server 2012 R2 and above are as follows:
Must use Windows Server 2012 R2 Hyper-V
Guest operating systems must be Windows Server 2012 or above and must be
running the Windows Server 2012 R2 Integration Services.
The disk must be VHDX, not VHD, and must be connected to an SCSI controller,
not IDE. It can be a generation 1 or generation 2 virtual machine.
VHDX can be fixed or dynamic but not differencing.
Can be used for data disks only. Cannot be used for operating system disks
The storage for the VHDX file being shared must either be a CSV or be hosted from
a Scale-Out File Server (SoFS) accessed using SMB 3 (the SoFS would be using
CSV for its backend storage). The reason CSV must be used to store the VHDX is
that the code to implement the VHDX sharing is part of CSV and not the regular
NTFS code.It is possible to force the process of loading and attaching the shared VHD filter driver
to a non-CSV volume. However, this loading will survive only until the disk is offlined
in some way, at which point you would have to load and attach again. Note that this is
not supported or even tested by Microsoft and should be used only in basic test
scenarios if a CSV is not available. Here are the steps:
1 . Install the Failover Clustering feature through Server Manager or through
PowerShell:
Install-WindowsFeature Failover-Clustering2 . Run the following command, specifying the volume to attach the shared VHDX
filter to:
FLTMC.EXE attach svhdxflt <volume>:Provided that a VHDX file is stored on a CSV volume or SoFS and is connected via an
SCSI controller, there is only one step to make it shared: After it has been added to a
virtual machine in the Advanced Features properties for the disk, select the Enable
Virtual Hard Disk Sharing check box, as shown in Figure 4.28. Repeat this for the
same disk on all virtual machines that need to access the shared disk.