Best Way To Back Up My FLAC Collection?

I'm just now getting to transferring all of my CD's to FLAC, and I'm using a backup combination of external HD (an old MyBook 320Gb) and extra space on one of my internal 1Tb HDs. I just schedule SyncBack to run a backup once a week, and I'm all set.

I considered backing up my FLAC's to RW DVDs, but that's a little too costly and kind of counterproductive considering I've already got CD copies  .

Anyone else? What is your guys' backup routines?

While an extra internal drive has a lot of benefits (it's usually speedier, and with raid 1 the backup is full and automatic) but a few important drawbacks as well. Basically it only protects against hard drive failure. If something else damages the computer (fire, lightning, ...) both drives are pretty much done for. An external drive for backup can be put in a different room or a safety deposit box or wherever you want. Depending on the type of data you may also have several external drives and rotate their usage. Given USB3 (or eSATA) your speed should be pretty high (if it's a major concern, check out benchmarks of the external drive/usb chip and of course your motherboard's USB3 chipset). Other options include tapes (only really an option for full backup/restore) or optical disks (many DVDs or one/a few bluray disks).

Personally I'd just use an external hard drive, especially if you can get a USB3 one. Just don't move it while it's in use, and be a bit careful with it while moving even when it's off.