Re: [smartmontools-support]your bad block HOWTO on smartmontools.sourceforge.net

[Bruce A. <ba...@gr...>]

I don't know the answer to your questions, though others on this list
might add something more useful or definitive.  But some comments are
below.  Please copy the list on future corrrespondence.

On Fri, 10 Dec 2004 lJo...@so... wrote:

> Dear Bruce, 
> 
> I've just read your badblockhowto.txt on the smartmontools website, and 
> found it really clearly written and helpful. I also noted that you would be 
> interested to hear if someone has tested this with other filesystems ... 
> 
> Well it seems this is what I'm about to do with a broken Reiser4 partition. 

Ouch.

> 
> But I have a bit of a problem, and I thought you might be able to give me 
> some advice from you extensive experience. The problem is that the corrupt 
> sectors I'm trying to fix seem to be on the superblock/boot record! If I'm 
> not mistaken I may loose some data - but this isn't the main issue. 

Often file systems keep multiple copies of the superblock.  So you may be
able to use a 'backup' copy.  I don't know if Reiser4 has superblock
backups or not.
 
> What I'm trying to find out is whether this will screw up the whole disk (if 
> the block is reallocated), because I won't be able to write a new boot 
> record/superblock to the beginning of the disk? Or will the disk be clever 
> enough to move the boot record somewhere else ... ? 

If the block is reallocated by the disk, this will be done 'transparently'
to the OS and file sytem.  The new block will have the same address as the
old one, but will be located 'somewhere else' on the disk.

BUT if the old block is unreadable, then information may be lost when the
block is reallocated.  However if there is a backup superblock somewhere,
you may be able to tell the file system to use that backup superblock
instead.

> Sorry to bother you, and I hope you can be of some help. I realise you're 
> not a support forum, but I don't know who/where else to ask! 

Others may be able to say more....

Cheers,
	Bruce