Remember comp.sources.hp48?

[Helix]

This was the subject of an excellent French documentary, entitled "do our computers have a short memory?" They explained that there is no digital storing medium that lasts a long time, they typically degrade after one decade. The best digital medium is the magnetic tape. The conclusion was that the only lasting solution consists in replicating data on numerous computers, and doing this periodically and indefinitely to avoid losing precious information.

For those who understand French, here is the documentary: https://www.youtube.com/watch?v=KCD1h8o7QTg