When we got Shared VHDX in Windows Server 2012 R2 we were quite pleased as it opened up the road to guest clustering (Failover clustering in virtual machines) without needing to break through the virtualization layer with iSCSI or virtual Fibre Channel (vFC).
First of all, you need to be aware of the limits of using a shared VHDX in Windows Server 2012 R2.
- You cannot perform storage live migration
- You cannot resize the VHDX online
- You cannot do host based backups (i.e. you need to do in guest backups)
- No support for checkpoints
- No support for Hyper-V Replica
If you cannot live with these, that’s a good indicator this is not for you. But if you can, you should also take care of the potential redirected IO impact that can and will occur. This doesn’t mean it won’t work for you, but you need to know about it, design and build for it and test it realistically for your real life workloads.