Managing Logins and Jobs After Role Switching (SQL Server)
When deploying a high-availability or disaster-recovery solution for a SQL Server database, it is important to reproduce relevant information that is stored for the database in the master or msdb databases. Typically, the relevant information includes the jobs of the primary/principal database and the logins of users or processes that need to connect to the database. You should duplicate this information on any instance of SQL Server that hosts a secondary/mirror database. If possible after roles are switched, it is best to programmatically reproduce the information on the new primary/principal database.
Logins
On every server instances that hosts a copy of the database, you should reproduce the logins that have permission to access the principal database. When the primary/principal role switches, only users whose logins exist on the new primary/principal server instance can access the new primary/principal database. Users whose logins are not defined on the new primary/principal server instance are orphaned and cannot access the database.
If a user is orphaned, create the login on the new primary/principal server instance and run sp_change_users_login. For more information, see Troubleshooting Orphaned Users.
Logins Of Applications That Use SQL Server Authentication or a Local Windows Login
If an application uses SQL Authentication or a local Windows login, mismatched SIDs can prevent the application's login from resolving on a remote instance of SQL Server. The mismatched SIDs cause the login to become an orphaned user on the remote server instance. This issue can occur when an application connects to a mirrored or log shipping database after a failover or to a replication subscriber database that was initialized from a backup.
To prevent this issue, we recommend that you take preventative measures when you set up such an application to use a database that is hosted by a remote instance of SQL Server. Prevention involves transferring the logins and the passwords from the local instance of SQL Server to the remote instance of SQL Server. For more information about how to prevent this issue, see KB article 918992 —How to transfer the logins and the passwords between instances of SQL Server 2005 and SQL Server 2008).
Note
This problem affects Windows local accounts on different computers. However, this problem does not occur for domain accounts because the SID is the same on each of the computers.
For more information, see Orphaned Users with Database Mirroring and Log Shipping (a Database Engine blog).
Jobs
Jobs, such as backup jobs, require special consideration. Typically, after a role switch, the database owner or system administrator must re-create the jobs for the new primary/principal database.
When the former primary/principal server instance is available, you should delete the original jobs on that instanceof SQL Server. Note that jobs on the current mirror database fail because it is in the RESTORING state, making it unavailable.
Note
Different instances of SQL Server might be configured differently, with different drive letters or such. The jobs for each partner must allow for any such differences.