I mirror my database on a single Adaptec 2740UW controller, using two $180 4.5 GB 7200K RBM LVD drives. I'll add a second controller someday, perhaps. If I have to go back to my nightly backup, I'm OK with that for now and frankly silent controller failures are rare. The real problem is that my machine will go down if the controller croaks. At the moment, I'm a step or two ahead of Ben in the backup department, as I backup on a UDMA drive (i.e. that's a different controller than the mirror) and ftp a copy to California and another to my home machine (I've got a DSL line) from the ISP's downtown Portland, Oregon office. It will take a really big earthquake to wipe me out...