Bad block -> file mapping

[Wilko Bulte]

On Sat, Feb 18, 2006 at 10:47:49AM -0700, M. Warner Losh wrote..
> In message: <200602181735.k1IHZOuj040864 at gate.bitblocks.com>
>             Bakul Shah <bakul at bitblocks.com> writes:
> : > I have a hard disk that's been in service a long time.  I recently
> : > installed the SMART monitoring tools.  On occasion, I get reports of
> : > LBAs it can't read.  I'd like to map the LBA to an actual file in the
> : > file system, if possible.  Does anybody have any tools that can help
> : > me with this?
> : > 
> : > I know I need to get a new disk.  In the mean time, I need to cope
> : > with these errors in a sane manner...
> : > 
> : > Warner
> : > 
> : > P.S.  Here's a sample report:
> : > 
> : > Num  Test_Description    Status           LifeTime(hours)  LBA_of_first_error
> : > # 1  Extended offline    Completed: read failure     8949         65818210
> : > # 2  Short offline       Completed without error     8948         -
> : 
> : Wouldn't bad block forwarding by the disk take care of this?
> : Generally you want the read of a bad block to return an error
> : but if you write the block the disk will automatically remap
> : this block to one of the spare blocks.
> 
> Correct.  That's exactly what I'm trying to do.
> 
> : What exactly are you trying to do by mapping a bad block to a
> : file?  Nevertheless may be fsdb will help?  You still need to
> : map LBA to the slice/partition offset.
> 
> Right, I've mapped the lba to a partition, and used badsect to request
> that at the next fsck the file that contains the bad block be removed
> and replaced with the file in BAD.  However, I'd kinda like to know
> which file that is.  If it is a boring file (foo.o, say), I'd dd the
> bad block with 0's and then remove it.  If it is a non-boring file,
> I'd try to recover it a couple of times, etc.
> 
> Once I have the file in BAD, I'd planned on overwriting it with 0's
> and then removing it if I could read the block again.
> 
> Maybe there's a better way to cope, maybe not.  I don't know.  Hence
> my question :-).
> 
> This is with an ata disk, btw.

Obviously.  But for intents and purposes it could have been an RK05 :-P
So much for progress

-- 
Wilko Bulte				wilko at FreeBSD.org