@Thomas,
You are right. I am writing the VM replication components based on CBT mechanism. Till now what i did that on the same ESXi machine : read the current VM's VMDK and write it to destination VM's VMDK. Copying only active blocks returned by QueryDiskChangedArea("*") API. This is working fine for me. If i pass the change id of previous snapshot and current snapshot MOR to QueryDiskChangedArea reporting the changed blocks.But when i read / write, changes are not replecting on destination VM. Still it is in previous state.
with thanks,
Santosh