I don't understand the question properly so this might be completly useless.
vhd is the MS hypervisor format is it not?
I don't know anything about vdh but it is my understanding it is the equivalent of a vmdk.
In vmware, each vm has at least one vmdk.
You can store multiple VMs (and thus their vmdk) into one LUN. Stick to 10 VMs to prevent locking issues. A good size for a LUN is 500Gb.
Mix workloads too if you can
Cheers
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