I'm interested in how well Active Directory would fare as the authentication backend for a website, scaled for ~1 million users. Do you have experience with AD in web environments of this scale, and if so what level of hardware would we need?
[Update] Regarding frequency of login: I agree that this is a key factor, but we don't have that information yet. Assume a regular commerce/banking site setup: login via a form once, carry your identity in a session (ie. no authentication calls to AD on pages other than login page).
The AD will not store a significant amount of user information beyond what's needed for authentication.
How busy are you expecting the website to be: Assume a normal commerce/banking site. No further information on this.
Will this AD be partitioned: It can be, although simplest architecture is preferred.
Will this AD be serving anything else: No.
How complicated will your OU structure be
Will you be extending the schema: The standard schema will be used. The OU structure will be fairly simple.
Will you be performing many searches on it: only to lookup username / email for a subsequent bind.
Will you be storing a lot of information against the User Objects: No
- Will exchange be involved with this AD: No