How do hard drives handle bad blocks nowadays?

[mbr-rRLCkWC8vypBDgjK7y7TUQ at public.gmane.org (MBR)]

I administered Unix systems for a while in the late 1980s.  I remember 
that when I had to configure SCSI disks I first had to run a surface 
scan to verify that all blocks on the disk were both readable and 
writable.  I'd then have to edit into the disk's bad block list any bad 
blocks encountered, so it could replace them with blocks in the spare 
track.  The tool I used for this was provided either by Sun or by the 
disk manufacturer.

It's now two decades later, and I'm trying to understand what's changed 
since then.  In particular I recently cloned a laptop drive (IDE) to a 
new drive.  When I did so, I encountered 2 bad blocks on the new drive.  
Based on my recollection from the late 1980s, I didn't think 2 bad 
blocks was a big deal because I assumed I could manually enter their 
addresses into the bad block list and they'd be replaced by spare 
blocks.  But I haven't managed to find a tool to allow me to examine 
and/or edit the bad block list.

After doing some web searches and a bit of reading on this, I get the 
impression that nowadays all modern drives implement S.M.A.R.T. 
(Self-Monitoring, Analysis, and Reporting Technology) and that using 
S.M.A.R.T. they all handle this behind the scenes.  If that's true, then 
presumably the only time I should ever see a disk report a bad block is 
when there are no more spare blocks left.  Am I right about that?

If so, then the fact that I encountered write errors on two blocks on 
the drive suggests that the brand new drive was in pretty bad shape to 
begin with.

Is there some tool that will allow me to examine the disk's bad block list?

Also, should I use 'dd' to test all blocks before I put a drive into 
service, or is there a better tool out there?

    Mark Rosenthal
    <mbr-rRLCkWC8vypBDgjK7y7TUQ at public.gmane.org <mailto:mbr-rRLCkWC8vypBDgjK7y7TUQ at public.gmane.org>>


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