Re: force remapping a pending sector in sw raid5 array

[Kay Diederichs <kay.diederichs@uni-konstanz.de>]

On 02/06/2018 07:14 PM, Marc MERLIN wrote:
> So, I have 2 drives on a 5x6TB array that have respectively 1 and 8
> pending sectors in smart.
> 
...
> # 3  Extended offline    Completed: read failure       90%       289
      1287409520

I have successfully used "badblocks" to overwrite bad sectors.

The variety of badblocks that comes with RHEL (there may be others!)
could be used with e.g.
 badblocks -svnb512 /dev/sdh 1287409599 1287409400
where
-n     Use non-destructive read-write mode.  By default only a
non-destructive read-only test is done.  This option  must  not  be
combined  with  the  -w option, as they are mutually exclusive.

I've adjusted the last-block and first-block numbers in the command
above so that they
a) encompass the known bad blocks
b) start and end on 4k-boundaries

This command leaves those blocks intact that still can be read.

After that, use a destructive-write badblocks e.g.

badblocks -sfvwb512 /dev/sdh <x> <y>
You'll have to adjust x and y to match just those blocks that cannot be
read, based on the output of the first badblocks run.

Afterwards, "smartctl -t short /dev/sdh" may clean up the SMART statistics.

HTH,

Kay