Why is it a minimum of 3 hosts for VMC SDDCs?

[gamename]

• [x] I am using the latest SDK version
• [x] This API is compatible with my vCenter version (You can get the info from '__vcenter_version__' in each sample)
• [x] I have searched existing issues and Troubleshooting wiki

Environment

• sdk package version:

  nsx-vmc-aws-integration-python-sdk 2.3.0.0.3.13851140 nsx-vmc-policy-python-sdk 2.3.0.0.3.13851140 pyvmomi 6.7.3
  vapi-client-bindings 3.1.0
  vapi-common-client 2.12.0
  vapi-runtime 2.12.0
  vmc-client-bindings 1.12.0
  vmc-draas-client-bindings 1.0.0
  vSphere-Automation-SDK 1.6.0

• python version:

  Python 3.7.4

• vSphere version:

• Operating System/Shell (used to run SDK-based apps):

Steps or code snippet to reproduce

I modified sddc_crud.py to accept a variable number of hosts. When I tried to create an SDDC with just 1 host, I get the following error:

Traceback (most recent call last):
  File "./samples/vmc/sddc/sddc_crud.py", line 229, in <module>
    main()
  File "./samples/vmc/sddc/sddc_crud.py", line 221, in main
    sddc_operations.create_sddc()
  File "./samples/vmc/sddc/sddc_crud.py", line 152, in create_sddc
    raise Exception(error_response.error_messages)
Exception: ['Sddc provisioning requires a minimum of 3 hosts.']

This seems arbitrary. Its perfectly possible to start a 1 host SDDC manually. Why not via the API as well? Remember that the difference between 1 and 3 hosts is a lot of money to the user. It would be really nice if we could avoid considerable costs by being able to implement single-host configurations.

[jmh666]

seems relevant, but still arbitrary

[tianhao64]

@gamename You should be able to create a one node SDDC for evaluation if you pass sddc_type parameter with value '1NODE'.

[gamename]

@tianhao64 Thanks! That worked.