General :: Combining A Badblock Scan With A Time Output

I have a Lenny Raid-5 setup, and I use rsnapshot to occasionally backup the raid to an old external hard drive that I otherwise leave unplugged. That external went bad, so I figured I should setup its replacement with encryption and keep it off site when not in use.

While googling and coming across LUKS, I can across this post this post that mentioned the drive should be be filled with random data before setting it up for encryption, and had the following as a potential sufficiently-good option over the time-intensive dd /dev/random route:
badblocks -c 10240 -s -w -t random -v /dev/sdx

I was unfamiliar with badblocks, and came across this post after a google session which noted the time duration of scan is an important factor as well as the result.

I sshed into the NAS, and was about to run badblocks first in read mode, then in write mode, but then I considered the time consideration. I was going to use something similar to the following: nohup badblocksstuff &

My Question: Is there a way I can append to the resulting nohup.out a time to complete value?