Re: Weird result while smart testing a Winchester Digital drive

Nathan Stratton Treadway <[email protected]>
Newsgroups gmane.linux.utilities.smartmontools
Message-ID <[email protected]>
On Sun, Jul 27, 2014 at 15:21:23 +0200, [email protected] wrote:
> User Capacity:    1,000,204,886,016 bytes [1.00 TB]                                           
> Sector Size:      512 bytes logical/physical                                                  
[...] 
> #14  Extended offline    Completed: read failure       90%     14484         4288352511
[...]
> 
> My partitionlayout is:
> 
> 
> Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0x07ec16a2
> 
> Device     Boot      Start        End    Blocks  Id System
> /dev/sda1  *          2048     104447     51200  83 Linux
> /dev/sda2           104448   12687359   6291456  82 Linux swap / Solaris
> /dev/sda3         12687360  222402559 104857600  83 Linux
[...]
> /dev/sda12      1491195904 1953525167 231164632  83 Linux
> 
> 
> With 
> 
> 4288352511 / 512 = 8375688 I found that the swap (/dev/sda) 
> partition has been affected by the bad sector.

Note that the "LBA" parameter in the self-test log is expressed in
sectors, so you should not divide it by 512 in order to map it into the
"Units: sectors" partition table.  As Christian pointed out, the LBA
value of "4288352511" here is bogus; the correct value must be something
below 1953525168 (and thus could be used without any division to find
the partition Start-End range it fell between...).


> dd if=/dev/zero of=/dev/sda2 bs=512 conv=notrunc                                              
>                                                                                              
> and it fails with an I/O-error at a certain point.                                            
>                                                                                              
> Another offline test shows my, that the bad sector was still there (no                        
> remapping).                                                                                   

Also note that if the write to the disk succeeds in remapping the
sector no I/O error will be generated.  Usually the sequence I go
through is something like
  1) try to read failed sector -> I/O error
  2) write to failed sector -> no error
     (at this point, the Current_Pending_Sector count will have gone
     down)
  3) read sector again -> no error

								Nathan 




----------------------------------------------------------------------------
Nathan Stratton Treadway  -  [email protected]  -  Mid-Atlantic region
Ray Ontko & Co.  -  Software consulting services  -   http://www.ontko.com/
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