[dnanian]

It's likely that a file is being aggressively written during backup, Ed. Please run, in Terminal:

sudo lsof | grep "SDCopy"

(Copy/paste) Press Return after if necessary, and enter your password followed by Return (it won't echo).

That'll print a list of the files we're copying. At the end will be the file we're currently working on -- which is the one causing problems. What file is that?