1st and foremost, just so you know, storing your files on a
striped array will cause you to be
twice as likely to have a failure that takes down the volume. You definitely want to
{read NEED TO} back it up.
I've gone with the buy a second drive approach since drives are quite cheap these days. Data doesn't change frequently enough to justify incremental backups. Losing a CD or two isn't that big a deal. And tapes that have the capacity to backup 100's of BG of data easily seem to be expensive. As for CDs or DVDs, you're still talking about a lot of media and swapping them in and out.
Get a drive and get a removable tray, as JLee suggests. Put it in, copy the data and then remove it so that you have an isolated backup.
What I'm probably going to end up doing is getting 2 of these devices:
http://www.areca.us/IDERAID.htm(HW RAID 5 device, uses 3 external 5.25" bays and holds 5 3.5" drives. With a big plus being that the arrays are convertable and expandable.)
I'll have one at home and one at work. Then I'll either manually bring one back and forth, or do rsync's between them.
One of the things that I've been thinking about with reguard to using a HD for backup purposes is that a HD could potentially fail while just sitting around, and you wouldn't know. I was thinking that by using the second HD, if it failed, I'd know and be able to get a replacement. Sure it would be more likely to fail, but I'd know right away.
kiwi