Input/output error

Jeff LaCoursiere jeff at
Sun Nov 24 22:53:48 GMT 2002

I am pretty certain that bad block mapping is handled by the controller in
the disk casing (whereas with SCSI it is up to the OS/SCSI controller, and
the controller in the case is basically stupid).  Now a guess - if you
start showing bad blocks on an IDE drive it has already used up all of its
bad block space, and the disk is ready for the circular file.  I think the
bad block list is usually a finite size...


On Sun, 24 Nov 2002, Paul Civati wrote:

> "Rob King" <robking at> wrote:
> > It looks to me as if there are some dud sectors? I ran an fsck:
> fsck is effectively checking the consistency of your data (filesystem)
> on the disk, this is different to checking the actual disk media/sectors.
> > So i ran a dmesg - and to my surprise... (I've pulled out the relevant 
> > lines):
> > 
> > ad4s1e: hard error reading fsbn 159012031 of 79505984-79506111 (ad4s1
> > bn 159012031; cn 9898 tn 10 sn 31) trying PIO mode
> Right.. that looks like bad media/sectors.
> > Anyone any ideas? I'm not having much luck with IBM drives at the moment
> > - at least one goes a year - this'll be my second!
> Well, this is tricky I think, because you're using IDE/ATA.
> Basically you need to map out those bad sectors to stop the o/s trying
> to use them, with SCSI disks you would eg. go into the Adaptec SCSI bios
> and run a verify, and it would scan the disk and mark any bad sectors
> as unusable.
> As far as I can make out, IDE/ATA doesn't really have this, you basically
> have to low-level format the drive and the format utility will take out
> the bad sectors at that point.  Often the manufacturers have their own
> utility for low-level formatting their IDE/ATA drives.
> When this happened to me I had a very very old disk and I couldn't find
> a specific utility so I used another manufacturers instead and it made
> an even bigger mess of the disk!  I think the disk was terminally broken
> though.
> I'm not sure how modern IDE/ATA drives handle bad media, but the above
> is what I gleaned when I went through the problem.
> Anyone know otherwise?  Time to ask google I think..
> -Paul-
> ------ FreeBSD UK Users' Group  -  Mailing List ------

More information about the Ukfreebsd mailing list