Migrating User Data to a New Debian Server

This paper presents the installation and configuration of a new server with the latest Debian operating system and user data migration from an old server with all functionalities and minimum unavailability of services such as e-mail. Long-term security and version updates as well as updates of the complete operating system usually bring quite many differences of system and configuration files. The result is a quite large number of obsolete or just unnecessary, not deleted files, as well as unneeded packages. All stated can slow the server down or even present security risks. The solution is an installation of a new server with all the latest needed applications, its configuration, and finally user data migration. The old server is working until the last moment. Finally, the old server is turned off and the new one is put in the production state. This action is measured in minutes so unavailability of critical services such as e-mail is also measured in minutes. After the procedure the users will notice an increase in server speed and the server's fresh installation guaranties error free operation and much lower security risks. At the same time the old files are not deleted which is important in case the old server should, if necessary, be restored to fully functional state.