Right now, we don’t plan to add this support but up-vote this and we could consider.Ron Wright commented
I know it is possible to attach a blob VHD (disk) to a VM that serves as an iSCSI target. Once the disk is attached to the iSCSI target it can then be used to create another VHD that is then configured to be accessed by two iSCSI initiators. However, this means putting a VHD on a VHD which is totally inefficient. I should be able to use my blob VHD as an iSCSI target directly.