bad sector in gmirror HDD

[Jeremy Chadwick]

On Sat, Aug 20, 2011 at 07:54:30PM +0200, Alex Samorukov wrote:
> You can run long self-test in smartmontools (-t long). Then you can
> get failed sector number from the smartmontools (-l selftest) and
> then you can use DD to write zero to the specific sector.

This is inaccurate advice.  I covered this in my reply already as well:

http://lists.freebsd.org/pipermail/freebsd-stable/2011-August/063665.html

Quote:

"The SMART tests you did didn't really amount to anything; no surprise.
short and long tests usually do not test the surface of the disk.  There
are some drives which do it on a long test, but as I said before,
everything varies from drive to drive."

TL;DR version: smartctl -t long  !=  smartctl -t select.

The OP's drive does not support selective scans (-t select), and long
turned up nothing (no surprise there either).  So, using dd to find the
bad LBAs is the only choice he has.

> Also i am highly recommending to setup smartd as daemon and to monitor
> number of relocated sectors. If they will grow again - then it is a
> good time to utilize this disk.

You have to know what you're looking at and how to interpret the data
smartd gives you for it to be useful.

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                   Mountain View, CA, US |
| Making life hard for others since 1977.               PGP 4BD6C0CB |