Kall that looks to be a pain in the butt.
On VMware you might as well make the .VMDK thin provisioned. Make the VMDK disk size the max your storage will support, i.e. if you have 30TB of space on it use 80% or 24TB and then on the DSM Volume configure that to what you need for the moment, i.e. Allocate Size 1000GB. In this way if you need to allocate more space on that Volume you just re configure the volume and key in the new Allocate size you need.
The Pool could be Basic(one disk ), JBOD(two or more disks) or RAID0(two or more disks). I really thing with VMware it will not matter the number of disks as you do not have multiple virtual SAS/SCSI controllers to spread the IO across.
