I just moved database to new instance of SQL Server (SQL Server 2012 Web from Amazon EC2) and am now cleaning up database users.
I am not sure if/why these 2 users are needed (they exist in original database):
- NT AUTHORITY\IUSR
- NT AUTHORITY\NETWORK SERVICE
Note that there are also 2 database schemas with exactly the same names.
I am more clear on
NT AUTHORITY\IUSR - this seems to be a user for IIS. IIS is not even installed on the new instance, so this one probably can be deleted.
I am not sure about
NT AUTHORITY\NETWORK SERVICE (or how it got created to begin with - new databases created on new server don't have it, or
Neither of these 2 users exist at server level on a new instance or on an old instance.