[hummerZ]

The only truly robust long-term archival system is one of perpetual (and redundant) migration towards newer standards.

For short to medium-term archiving, large disk arrays with parity/redundancy are a great solution, provided that the system is well-maintained, and that drives are cycled out as needed.

The problem with tape systems (as people have already pointed out) is that they are mostly proprietary, and are phased out far too quickly to be relied upon as a single solution. Your G3/Mezzo/Retrospect system will not be around in 30 years, believe me. For that matter, neither will AIT, LTO, exabyte, etc.

And I agree that for non-enterprise archiving on a budget, the best option at the moment is a combination of optical and hard disk backup.