As you can read in the book, I decided to store the Redmine code for the book’s project in the directory /opt/redmine/redmine-x.y.z, where x.y.z is the version number. I chose such location to be able to easily switch back to the previous version of Redmine in a case of upgrade failure.
However, such approach introduced a need to copy all the user and state data, such as logs, from the old version to the new one during the upgrade. And, there are quite a lot of such data. So, to simplify this process, I decided to modify the Redmine file structure a little.