[Gllug] JFS and bad blocks

[Chris Bell]

On Wed 05 Oct, Martin A. Brooks wrote:
> 
> Jack Bertram wrote:
> > I can't seem to work out how to test a JFS filesystem for bad blocks and
> > mark them bad. Anyone using it and can give advice?
> 
> 
> I may be misunderstanding but what do bad blocks have to do with a 
> filesystem?
> 
> All modern hard disks remap bad sectors on the fly.  This is (allegedly) 
> one reason why manufacturers quote hard disk capacity as 10^n rather 
> than 2^n.  The overhead gives them unused sectors to remap to.
> 
> If a disk had a bad block that's exposed to the host then the filesystem 
> is irrelevant - all filesystems using the partition containing the bad 
> block will be affected.
> 
> Perhaps you mean that you want to have the filesystem exclude writing to 
> blocks that are known to be bad?  If so then you either have an old disk 
> that doesn't do on-the-fly remapping or your disk has run out of sectors 
> to remap to.  In either case you should seriously consider simply 
> replacing the hard disk - they are stupidly cheap these days.
> 
> Or did I miss the point?
> 
> Mart.

   I have had more than one disc which appeared to have loads of duff
sectors, and trying to format them took ages because the heads were
continually seeking replacement sectors. In all cases they had been rejected
after use in a M$ PC. They showed as fault free after I formatted them as
single partitions and then ran

mke2fs -c -c

so I suspect that there is a faulty sector list that is accessible and
rewritable.

-- 
Chris Bell

-- 
Gllug mailing list  -  Gllug at gllug.org.uk
http://lists.gllug.org.uk/mailman/listinfo/gllug