3.2. 기존 데이터를 백업하십시오!

Before you start, make sure to back up every file that is now on your system. If this is the first time a non-native operating system is going to be installed on your computer, it is quite likely you will need to re-partition your disk to make room for 데비안 GNU/리눅스. Anytime you partition your disk, you run a risk of losing everything on the disk, no matter what program you use to do it. The programs used in the installation of 데비안 GNU/리눅스 are quite reliable and most have seen years of use; but they are also quite powerful and a false move can cost you. Even after backing up, be careful and think about your answers and actions. Two minutes of thinking can save hours of unnecessary work.

멀티 부팅 시스템을 만든다면, 기존 운영 체제의 배포 미디어를 가지고 있으십시오. 보통 그럴 필요가 없겠지만 시스템이 부팅하려면 부트로더를 다시 설치해야 할 수도 있고, 최악의 상황에서는 전체 운영 체제를 다시 설치하고 백업한 내용을 복구해야 할 수도 있습니다.