Can you clarify exactly how the 6 1TB HDDs are configured in your 3 RAID 0 VDs? How are you upgrading from the 1TB to 4TB for VD1? Is this a single HDD in a multiple HDD virtual disk? You know that a single HDD failure in a RAID 0 VD is catastrophic, correct?
Since you have a backup can you simply reconfigure with the new disks you're planning on and create a new VD and restore the data?
I'm concerned that the back and forth with the disks has resulted in metadata corruption leaving no configuration on the virtual disk to import.