On 04/25/2013 12:09 PM, Yasha Karant wrote:
>>> You'd presumably want the "non-destructive" tests...
>>
>> smartctl -t long is probably a better option.  If a small number of bad
>> blocks are detected they should be swapped out by the drive itself
>> meaning they are transparent to the FS.  You won't see any of that with
>> badblocks.
>>
>> Jeff
>
> Such blocks swapped out by the hardware controller built into the hard
> drive (the controller to which the computer hard drive interface
> controller communicates -- e.g., the SATA controller on a motherboard)
> might or might not be transparent.

Correct.  I didn't mean "transparent" as in no data is lost.  I meant 
that if the HD controller can't _read_ that block it will substitute a 
spare block for future _writes_ to that block so there is no benefit for 
the filesystem to mark that block as bad -- even if it was bad at some 
point in the past.

Once the controller has run out of spare blocks then running badblocks 
might be a beneficial thing, though I would argue the drive is well 
along its way to catastrophic failure by that point and it should simply 
be replaced.

Jeff