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Here is the text from “Microsoft Dynamics AX 2009 Installation Guide”
Install an AOS instance on multiple computers
For most production environments, you will install multiple AOS instances, each on a different
server. You can use multiple AOS instances to support batch processing and load balancing. For
details, see the Server and Database Administration Guide.
Install each AOS instance as described in Install an AOS instance. Point all the AOS instances to
the same application file location and the same database.
You can use a single domain account for all instances of the AOS service or you can specify a
different account for each instance. We recommend using a separate domain account for each
AOS instance.
If you use multiple accounts, you can create a group in Active Directory to more easily manage
AOS account permissions. Use the following procedure to set up permissions for the Active
Directory group.
1. Create a group in Active Directory.
2. Add the AOS accounts to the group you created.
3. Make the Active Directory group a login on the database server.
4. Make the login a user in the Microsoft Dynamics AX database, and add the user to the
following database roles: db_ddladmin, db_datareader, and db_datawriter.
5. Grant the Active Directory group full permissions to the folder that contains the application
files.
6. Optionally, remove permissions on the application folder and in the database for the
individual AOS accounts.