In case you didn’t notice, Microsoft changed the Supportability statement around ADFS farms that run on a Windows Internal Database (WID) backend.
Previously, WID-based ADFS farms were limited in support for the amount of ADFS servers you could run and the maximum number of Relying Parties you could register.
- A maximum of 5 ADFS Servers, if you are running more than 10 Relying Parties.
- A maxiumum of 5 Relying Parties, if you are running more than 5 ADFS servers (max 10).
pretty narrow – and limiting in the way you can build ADFS farms in WID. Microsoft were taking it on the safe side, to ensure you do the right thing and design your critical ADFS farm on SQL – which pretty much endlessly scales, should you need additional capacity.
There is also SQL Server support for additional features, that today cannot be used with WID-based farms:
- Token Replay Detection
- SAML Artifact resolution
Now – Microsoft reviewed their supportability statement and tested how far they could go with WID. Apparently, they found WID could be pushed a lot further than initially allowed, while keeping performance and WID replication intact. The new limits for WID-based ADFS farms are: