Hey JohnMy apologies for the confusion as you are correct. For the VA(Virtual Appliance) deployment, NFS is the only supported backup server at this time. This is for both automation and assurance.  

Hi SeanAt this time, the minimum requirements are noted in Table 1 of the deployment guide: https://www.cisco.com/c/en/us/td/docs/cloud-systems-management/network-automation-and-management/catalyst-center/catalyst-center-va/esxi/2-3-7/deployment-guid...

HelloAt this time we are limited to the supported servers noted in the guide.Catalyst Center (Virtual appliance): https://www.cisco.com/c/en/us/td/docs/cloud-systems-management/network-automation-and-management/dna-center/dna-center-va/esxi/2-3-7/adm...