While using OS authenticated user, you have to add the ArcGIS Server account to the geodatabase, then grant it permissions to the resource that it needs to access. When the service runs, it will log in to the DBMS as the ArcGIS Server account. The way that you add the ArcGIS Server account and grant it permissions varies depending on what type of ArcSDE geodatabase you are using:If you're working with an ArcSDE geodatabase (enterprise), the way that you add the ArcGIS Server account as a valid user of the database varies depending on the DBMS that you are using. You may find it helpful to consult your DBMS documentation to learn how to grant access to an operating system account. Making your data accessible to ArcGIS Server:http://resources.arcgis.com/en/help/main/10.1/index.html#//01540000039r000000Once you've added the ArcGIS Server account, you need to grant it SELECT permissions to the resource that you are going to publish. Additional permissions may be necessary if you will be editing data.Permissions for database servers.