Added MSDB limitation explanation

Author: urosmil

articles/sql-database/sql-database-managed-instance-transact-sql-information.md

@@ -531,6 +531,26 @@ The following variables, functions, and views return different results:
 
 The maximum file size of `tempdb` can't be greater than 24 GB per core on a General Purpose tier. The maximum `tempdb` size on a Business Critical tier is limited by the instance storage size. `Tempdb` log file size is limited to 120 GB on General Purpose tier. Some queries might return an error if they need more than 24 GB per core in `tempdb` or if they produce more than 120 GB of log data.
 
+### MSDB
+
+The following MSDB schemas in managed instance must be owned by their respective predefined roles:
+
+- General roles
+  - TargetServersRole
+- [Fixed database roles](https://docs.microsoft.com/sql/ssms/agent/sql-server-agent-fixed-database-roles?view=sql-server-ver15)
+  - SQLAgentUserRole
+  - SQLAgentReaderRole
+  - SQLAgentOperatorRole
+- [DatabaseMail roles](https://docs.microsoft.com/sql/relational-databases/database-mail/database-mail-configuration-objects?view=sql-server-ver15#DBProfile):
+  - DatabaseMailUserRole
+- [Integration services roles](https://docs.microsoft.com/sql/integration-services/security/integration-services-roles-ssis-service?view=sql-server-ver15):
+  - db_ssisadmin
+  - db_ssisltduser
+  - db_ssisoperator
+  
+> [!IMPORTANT]
+> Customers must not change the predefined role names, schema names and schema owners as such action will break the normal operation of a managed instance. In such occurrences SLAs cannot be guaranteed.
+
 ### Error logs
 
 A managed instance places verbose information in error logs. There are many internal system events that are logged in the error log. Use a custom procedure to read error logs that filters out some irrelevant entries. For more information, see [managed instance – sp_readmierrorlog](https://blogs.msdn.microsoft.com/sqlcat/2018/05/04/azure-sql-db-managed-instance-sp_readmierrorlog/) or [managed instance extension(preview)](/sql/azure-data-studio/azure-sql-managed-instance-extension#logs) for Azure Data Studio.