You better not be doing that kind of work on an ATA controler and talking about how imperitive it is not to loose data! ( since you are doing RAID5 I am guessing its a SCSI array with a controler that has some meat to it. Even then, "its all about the config". the new Dell Perc 3di and above controlers all rock for doing auto config rebuilds off the disk setup, but I know Mylex suck at that.
Because in reality the chances of loosing a controler config is much higher than loosing a drive. Some weirdness on a PCI buss, or just a controler freak out or BIOS twitch could send that config into neverland (yes the scary Michael Jackson playground of doom)
RAID5 has the nasty drawback of either: 1. terribly high CPU use on "soft" controlers, or controlers with bad drivers. and 2. Slow write speeds to the disk. ( the write speeds arent much better than one single disk alone I have found) this is also why most high end DB mfg's do not recomend running the DB on a RAID5.
to me performance is as important as stability ( which is why I run SCSI... its the perfect blend of both). I would not sacrifice performance to give me a 1 disk tollerance. RAID 3 in some respects is better than 5. Less CPU use, less Controler CPU use, and you still get the one drive redundancy.
Duplexing is where its at though, if you got the money, and the hardware, nothing beats it. a Mirrored Stripe. but if you are working on 500MB PSD's I am guessing there is some money there anyway
