As far as tape goes there are two options - DDS or LTO.
The difference between the two is based on the quality of the system. DDS is generally cheaper than LTO, but in the long term is more expensive due to the limited lifetime of the tapes used. I have also found them less reliable than LTO.
DDS operates on a similar basis to tape cassettes where there are two reel built into the tape and it passes from one reel to the other. With LTO tapes there is only one reel in the cartridge, the other reel being in the tape drive itself. At the start of operation the tape is spooled from the cartridge spool into the machine spool. When backups take place the tape is spooled back into the cartridge, being written to as it passes over the tape heads. As a result, the data on the tape gets maximum protection from errant magnetic fields as the data is writtent to the deepest part of the tape on the spool.
LTO tapes have an expected life of 100 hours of reading / writing, whilst with DDS it is 20. Both exceed this, but are a guideline.
LTO2 tape drives and tapes are very reasonably priced nowadays and have a 200gb / 400gb (uncompressed / compressed) capacity. I would recommend LTO over DDS for reliability.
Snibborg
