We want to migrate all of our users in SharePoint to ADFS. Our farm has 22 site collections. I have a script that uses Move-SPUser to migrate each user. We have over 7,000 accounts to migrate and I wanted to know exactly what this command is doing.
For instance, does it "replace" all the users in the user profile service and in all the site collection user information lists, as well as setting all the direct permissions and SP groups? Or, does it just "update" this information in the user information list (thereby maintaining the existing permissions), add the new profile to the UPS, then delete the old one?
Also, does the command hit every site collection in the web app or does something need to be done at each one?
[Edit: I verified when you use Move-SPUser, the user account in all the user information lists (if it exists) of all site collections is updated to the new account.
I am trying to determine our risk factor with migrating so many users at one time. If the command is executing all kinds of complicated logic all over in SharePoint, we might choose to do small blocks of users over a period of time so we can test them. We just didn't want users to have to select between NTML and ADFS when they open SharePoint, and that would be the case temporarily until the migration is complete.
Lastly, is this command pretty reliable?
Any information is appreciated.