You may not see it written but it is part of quality records and often document control. In QS-9000 contingency plans require.
Yes - you have to have a backup system commensurate with your system(s). Small company? Keep floppies of important stuff in a 'safe' place. Any more, particularly with companies over 50 people, they look for 'off site' storage (which can be the trunk of a car in the parking lot). 'Normal' is something like daily network backups (don't forget people's PeeCees) with a 2 week history (14 tapes at 1 tape per daily backup).