cloning a drive with dd

[Al - image hosting services <azick%zickswebventures.com@localhost>]

Hi,

I am setting up a server for a local Habitat for Humanity. The server has
2 drives and I was going to use the second drive as a backup. Then I got
an idea, why not build the kernel with root on wd0a and clone the drive?
If the first drive was to fail, then the second drive should work as a
stand alone. I found an example, but it wasn't from a NetBSD site. I was
going to boot from the live cd and use:

dd if=/dev/wd0d of=/dev/wd1d bs=32k conv=noerror,sync

But from what I remember it was really easy to trash both hard drives with
this and was wondering if this is the best way to do it.

Thanks,
Al