Also I have to disagree with Jun that DLT are good...
DLT is an amazingly old technology that is expensive, inconvenient, and finicky.
For instance, the tension on a wound tape is critical - if you drop a cartridge and the tension is sufficiently stuffed, you can actually break your DRIVE.
Also, it can be very slow for network backups if you can't stream data fast enough for the tape. The tape speed is so high (due to it being linear) that every glitch in your data makes the tape have to slow down, overshoot, rewind back past the point far enough so it has enough distance to get up to speed, then get going again. That said, big buffers help a lot.
Plus the media is rediculously expensive.
My preference is to use AIT drives http://www.aittape.com/ - not only is the memory chip cool, but it is awesome for random access and tape loaders - if your software supports it.
Of course DB backups/restores don't really need all that much random access...
I have heard good things about exabyte mammoth drives http://www.exabyte.com/, and they have cheaper drives and media than ait - but I have never tried them myself.
