Thanks for the posting your "diskutil list" output; it enabled me to tailor this command for your fusion drive.

Code:
sudo dd if=/dev/rdisk1 of=/dev/null conv=noerror bs=1024000
  1. If you've never run "sudo" before, Terminal will pop up a warning along the lines of you're risking starting a nuclear war between Bora Bora and Pago Pago if you do something wrong; just click past it.
  2. Terminal gives you no indication that you've entered your p/w...no dots, dashes, or stars; just hit return after you've entered it.
  3. A traditional surface scan runs one 512 byte block at a time and can take an awfully long time depending upon various factors, so to speed this up, I've defined a block as 1,024,000 bytes; if you've got bad blocks, it's output won't be fully detailed, but you can rerun it in exquisite detail if that turns out to be the case.
  4. joemike is spot on about the critical factor being newly developed bad blocks, but since your drive has never been scanned (I assume), the best we can do is whatever comes up.
If you'd like to set your head spinning, you can read through Surface scan doesn't run from Terminal? and Permission Repairs Error Messages.

The new Great Equalizer is the SEND button.

In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire