Even real gurus do mistakes at some time, so they better prepare backups before files are lost in space. As HDDs get cheaper, more and more admins prefer to buy a number of large disks and simply copy all data to those. There's a real benefit: if you make them available read-only to your users, they may just copy a file from two days ago off your store without asking you for recovering a backup.
Nonetheless, tape drives are available with high capacities today, so they're still used all over the world. In turn, you'd better know how to use them. So here are some "do"'s and "don't"'s about tape cardriges and tape drives.
Tape drives need to be cleaned regularly. To clean them, you're expected to insert a cleaner cardrige from time to time. Some drives will signal a LED when cleaning is neccessary, some don't. Consult your drive's documentation about how often (or after how many hours of operation) cleaning is needed.
Linux presents you with two types of char devices for each tape drive: /dev/st0 and /dev/nst0. "st" is for "SCSI Tape" (because there are virtually only SCSI tapes available which won't break every two weeks...), "0" is first tape drive. If you access the st device nodes, the tape will be rewinded to it's start after the device node is closed by any accessing application. The "n" in nst is for "non-rewinding" access, so after use, access to these nodes won't rewind the tape.