hard drive diagnostics: Multiple read test with EStools

I'm using the diagnostics software EStools from Samsung to check a
Samsung hard drive health. Sometimes the hard drive fails to the
"Multiple read test" saying Bad sector. I would like to know what is
actually this "Multiple read test". The software doesn't give any
information such as that bad sector address. Is there another tool which
would do the same test but with more details?
I used EStools from the latest UBCD release. Among all programs for hard
drive diagnostics on that CD I have not found any doing both this
"Multiple read test" and supporting Samsung hard drives.