Installation and Upgrade > Installation and Configuration Guide - Update Existing Installation > Planning Before Updating an Installation > Using Both Test and Production Systems
  
Using Both Test and Production Systems
PTC recommends that you always use a test (pre-production) system to ensure that your Windchill products are operating as expected before deploying them in a production environment. On the test system, you can make needed site modifications before moving the system into a production environment. You should always maintain the same set of Windchill products on both your test and production systems. This allows you check out potential issues on the test system without interfering with production system activities.
Installing a maintenance release involves updating code in both your main Windchill directory (the directory where your Windchill solution resides) and, possibly, in other directories (depending on which Windchill products you have installed). Be sure to install the maintenance release on all systems that comprise your Windchill solution.
Using the test system allows you to incorporate updates from PTC into any site-modified files, and validate the maintenance release with your own customizations without interrupting work being done on your production system. PTC recommends that you store a copy of all site-modified files in a safe area directory structure under the Windchill installation directory. Then, by running the PTC Solution Installer with the service pack installation type option of "Update Existing Installation," you have access to the files that PTC has changed for the maintenance release and you can update your site-modified files accordingly. After updating your site-modified files on your test system to verify that the updated system, incorporating your site modifications, works according to your requirements.
After you have installed the maintenance release on a test system and are satisfied with the results, you can copy the site-modified files that you have updated to the safe area directory on your production system. Then, you are ready to repeat the maintenance release installation process on your production system. Because of the work you did on your test system, installing the maintenance release on your production system should take less time.