Upgrading XenDesktop from 7.1 to 7.5
1. First Copy the setup file locally (Recommendation is to copy it on local disk) Since we already have an existing installation of XenDesktop 7.5 Which is having all these roles (Director, License Server, StoreFront, and Studio). Double click on Auto Select and start the installation.
2. Then it will prompt you a license agreement window, accept the licence agreement and click next to proceed further. 
3. Following are the steps below to upgrade the XenDesktop from 7.1 to 7.5 :
[1] Back up the Delivery Controller databases [2] Upgrade the Virtual Delivery Agent and perform an image update on all master images [3] upgrade half of the delivery Controllers (all components) [4] use the upgraded version of studio to perform the site upgrade, and then finally [5] upgrade the remaining Delivery Controllers (all components).
Click on ready to continue check box and click next. 
4. Here you will get a License Message (Upgrade your license server first which is recommended) .Click on let me continue check box and Next. 
5. click on Automatic configuring firewall rules and click next. 
6.You can review the prerequisites and click on upgrade. 
7.Then you can see the upgradation installation process completing .This will upgrade all the Core Components and installing component initialization post Installation and click on finish. 
8. After installing you can launch citrix studio. 9. Click on automatic site upgrade . 
10. You will get a new window for Upgrading a site and click on ready to upgrade. 
11. Then it will prompt you a progress bar for upgrading your site. 
12. After successfully upgrading it, the below screen is prompted, then click on Test site and do the validation. DDC is successfully upgraded. 
