I've not used
dd all that much, but so far it's not failed me yet. Right now, I've had a
dd going for over 12 hours - I'm writing an image back to the disk it came from - and I'm getting a little worried, as I was able to
dd from the disk to the image in about 7 hours.
I'm running OSX 10.6.6 on a MacBook with a Core 2 Duo at 2.1ghz/core with 4gb RAM. I'm reading from a .dmg on a 7200rpm hard drive (the boot drive), and I'm writing to a 7200rpm drive connected over a SATA-to-USB connector. I left the blocksize at default, and the image is about 160gb.
EDIT: And, after 14 hours of pure stress, the
dd worked perfectly after all. Next time, though, I'm going to run it through
pv and track it with
strace. Thanks to everyone for all your help.