Separate servers for 9iAS and customer database?

Should 9iAS and the customer database be on separate servers? Do you have any best practices?

Best practices are variable at times. Normally, you want the database on one server, the application server on another (and the Web cache on still another). However, it all depends of the capability of your server and the application you are using. We have clients with the customer database, the infrastructure instance and the middle tier instance on one server. It works fine because the server can handle the load. The difference between one server and two is strictly the server's ability to handle the load. There is no redundancy or high arability gained by only two servers.

If you believe that your system will grow in the future, then use two servers as this will allow you to easily add additional application server tiers for load balancing.