You can change the location of the .proi directory by setting the variable as follows in a startup batch script:
set PDM_LDB_PATH=destination path
Keep in mind that each user will need their own .proi location. You can use a variable like %user_profile% in the destination path if your users have their own computer logins.
Typically, the .proi is stored locally for performance reasons. There may be other issues with creating a backup of the .proi also. Standard practice is to simply require users to check in theirchanges on a regular (daily) basis. Then the changes will be covered by the server database.