that will need no precaution, there will be people that will defend technology/science. Try to destroy a teenagers Ipod and you will learn the definition of war (lol).
People wont let civilization slip without a fight. The only way that all science and technology could be lost is if those who would want it destroy it in their conflict over it.
Even in some kind of post-Apocalyptic world there would be some kind of stronghold where technology would still remain (such as a small town with solar power and basic computers).
and if civilization was really at risk i know many people that would begin to carry flash-drives of important data(like combustion engines, electricity, irrigation, radio, etc) on necklaces or in place of other jewelry
just the people that I know would carry at least 500gb.
i could see it becoming some kind of movement (the more commonly thought important data would have thousands of copies) where it would be almost impossible to destroy not only all the saved data but the knowledge of people that would pass reading and such to their children.