My university recently updated EzProxy from a very outdated version to a new one and at the same time we decided to update the name of the server that was hosting the proxy (mainly because our university has been renamed recently, so the domain name changed and the old one is becoming more outdated every day).

OCLC offers documentation on how to install EzProxy on the new server so no problem for this. Afterwards it is quite easy (even if sometimes boring...) to go and update the links to use the new proxy on our tools but it becomes more complicated when it comes to the links that are outside our scope (bookmarks on user's browsers, links in teacher's bibliography ...). The easiest way would have been to shut down the old server and force users to find by themselves the new link, but we were not very happy with that solution.

What we have done, instead is :

• fix links whenever we can;
• remove all database definition from config.txt on the old server so that users are redirected to pages we can control;
• on the old server, in the docs folder, replace (or create) badhost.htm, menu.htm and needhost.htm with pages explaining the changes, telling users to update their bookmarks and displaying the new url. The method to construct the new URL differs for each file, so feel free to grab the files we used, available (on Gist or for download as a zip). They are in French but the important part is the
  section and the javascript that take care of displaying correct URL depending on the context of the template. There is a jquery section at the end of the page that calls a remote script that is sending me an email with the source of the request. It was useful to see during the weeks after the move the decreasing numbers of users arriving on these pages, and identify the origin of the remaining requests to see if we were able to fix the source link. But this could be done using the logs I assume.
  • when the number of users arriving on this server becomes low, ask our IT department to update the DNS so that everything is redirect to the new server without the user noticing the change and shutdown the old server!

  Hope that helps!