What to consider when adding Retail Cloud Scale Unit (RCSU) to a Storefront 365 implementation

About RCSU (Retail Cloud Scale Unit) 

If you're using a Tier-2 sandbox or production environment that has application version 8.1.2.x or later, you must initialize Retail Cloud Scale Unit (RCSU) before you can use retail channel functionality either for point of sale (POS) operations or for e-Commerce operations that use Retail Server in the cloud. Initialization will deploy a Retail Cloud Scale Unit.

There are some steps that must be performed and validated when adding a Retail Cloud Scale Unit module to an existing implementation of Storefront 365. Based on experience, these are the three tasks that need to be performed.

1. The Anonymous flag of the IIS site is reset during the installation. Microsoft must set the flag to allow anonymous access.
2. The web.config file must be updated to allow anonymous access. This also includes anonymous access to the metadata.
   
   

   <add key="AllowAnonymousMetadata" value="True" />
   <add key="IsAnonymousEnabled" value="True" />
   

3. The payment connector assemblies used in the omni solution must be re-distributed by Microsoft or the Dynamics partner to be recognized by the RCSU.
   
   There is currently an issue waiting for a solution by Microsoft, that using the RCSU gives an exception that the payment connector selected is not found during checkout.
   
   
4. Full replication of the channel database must be performed.

For information about the Retail Cloud Scale Unit, see https://docs.microsoft.com/en-us/dynamics365/fin-ops-core/dev-itpro/deployment/initialize-retail-channels