Seeing this is linux thread I want to share my experiences as well. I use linux for my research because all the servers in my lab are linux based. Cant imagine my life without ssh and terminal. Anyway lets get to the point. Linux will break sometimes leaving you no option but reinstall it especially during version upgrades.So think ahead and while installing linux make sure that you make atleast 2 partitions. 1./(root partition) 2./home (home partition to keep all your data). Next time you install linux you just need to format your root partition and data in home partition will be saved.