Check Disk Health during System Boot

[Trevor]

How can I go about checking the health of the disk, that contains the root file system, during bootup, using something equivalent to fsck or badblocks?

[Trevor]

Travis,

As always, your responses are a tremendous help!

The author's exclusion of the value 4 is definitely understandable.
The exclusion of the value 6 is something that I can't quite put
my finger on - the only thing I have at this point is that the '6' key
on the keyboard wasn't working

Okay, I'm going to begin another post, focusing on tune2fs.  This 
one is starting to get a little long anyway.

Thanks Travis for the weekend wellwishes.  Hope you have a 
tremendous weekend as well!