Hi @ranujain, Not sure what version of Morpheus you are running but I did some quick testing in 5.5.3 and I find that I can pass the storage type without issue using a manual option list like the one you have above. This allowed me to select the size and type and provisioned to those values without issue.
What didn’t work was setting the storage type to an invalid type to get it to not add the storage in AWS. So if I had 5 disks in my spec and only wanted to provision 3 using the info above it would not work in AWS. For me in my limited testing I would get back an Unsupported volume type. There are other ways to accomplish this like using a script in the configuration phase that edits the payload. You can see some examples of this at Edit Instance Configuration Before Deployment.