Oh well... I just got two Seagate ST31000340NS (1TB disks) and because I ordered them online instead of buying in the local store, I decided to test them for medium errors first. When there would be errors, I could send them back within 14 days without any other reasons.
I issued 'badblocks -w -p 16 -s -c 16384 /dev/sda', but I don't think that I will wait that long until all 16 passes have been run, because:
Reading and comparing: done
Testing with pattern 0x00: 84.11% done, 26:11:28 elapsed
After 26 hours the first pass didn't even finish. *sigh* ;)