You heard wrong. I would never even consider storing my data on mag tape any longer.
Any type of magnetic media is far more susceptible to damage over time than optical media. I used to use 9-track tape a lot on a VAX system and constantly had problems with it. I would write files to tape one day and not be able to read them the next even though I verified them when I wrote them.
Whoa, forget that. Tape backups are really unreliable. I have been managing IT organizations for 30 years... You don't want to go there. Try three external hard drives (like plug in USB that have there own power supply), keep one off site. You can get 2-3 TB drives for ~ $100. Start with one, then when you realize how vulnerable you are buy anothere... Repeat. JD