80G drives are so cheap. Heck 250G and 500G drives are cheap now.

The more drives you have, the closer you are to failure for any one of them. It's all about statistics and MTBF. If you have 5 drives, each with an MTBF of 5 years, your total MTBF for any one drive is 1 year. With 6 drives, your MTBF is less that one year.

Here's what you can do. Reduce the number of drives. Use RAID for reliability on the data server, with a hot spare that software can swap in when needed. Backup all your data (goes without saying, right?)

RAID can be done either in software or in hardware. Either one works.

-David