That's the least important part about my post. I mentioned several things, one being the shell you probably already have running, that all will do a perfectly fine job - to hopefully demonstrate that.
'cp' is sparse aware. Yay. Is that a good thing, actually? If the source has zeroes, I want to write zeroes. Not sure... probably fine. I've been awake too long.
'ddrescue' is special, but again, consistency is key. I don't really care how it's copied. I just question 'should' - there are advantages elsewhere.
edit: My main gist is this - living off the land applies here, too! Whatever option is available. Make the copy, check the checksums. Pull out the bigger gun if necessary.
Never know when you have to rely on some binary that's surviving only in caches. Stuck with a broken system and no live environment in sight.
There is, however, something special about `ddrescue` (note that there are 2 different projects named thus; I don't remember the difference) - it does all the okay sectors, then goes back and retries bad sectors.
Just be sure to store the ddrescue state file somewhere persistent.
dd can copy block by block from one block device to another
ddrescue can do the same, but will handle errors better
e2image understands ext2/3/4 filesystems and can copy only the blocks in use, which can really help (though don't know how it works if it encounters an error)
The correct abstraction is that a file is a device. A file is a section of a hard disk which behaves like a whole disk. It also happens to be expandable.
cp's default behaviour for device files also happens to be very stupid.
