input/output error on hd

Jerry McAllister jerrymc at
Sun Feb 25 03:03:04 UTC 2007

On Sat, Feb 24, 2007 at 06:12:39PM +1100, Ian Smith wrote:

> On Fri, 23 Feb 2007, Jerry McAllister wrote:
> Jerry, just on a couple of points:
> Me to Marty:
>  > > Does the above result mean that my boot sector is ok?
>  > 
>  > I think maybe you might be getting some of your terminology shuffled 
>  > around.    Your boot sector is not at question here.   It doesn't
>  > affect the ability to read the disk partition.
> I was talking about sector 0 on ad1.  If the disk were bootable it would
> be the 'boot sector', but it's not bootable.  It still contains the DOS
> partition table though.  boot0cfg -v <drive> shows this info too.

OK.   Yes, he already worked on the sector 0 earlier.  
The DOS partition table is what is called the slice table in FreeBSD.
That seems to be OK - as I noted.


>  > Secondly, it looks like the slice table - which is what fdisk mucks
>  > with - is OK.  
> Luckily .. though with only one slice on the disk, easily recreatable.
>  > What seems to be messed up is either the slice 1 label which contains
>  > the partition table.   In fact, with one of your postings, it looked
>  > like it thinks it is slice 4, but I don't remember what you did to
>  > get that.   
> Try 'fdisk ad0sY' where Y is any freebsd slice, and you'll get that (or
> at least, I do on both my ad0 freebsd slices).  Maybe fdisk should barf
> or at least whinge rather than reporting the first sector of any slice
> specified as if it were a sector 0 / MBR / boot sector?

Probably should barf or make some other error message.  Anyway, one
shouldn't run fdisk on a slice, but on the device, so that accounts for
the weird message I suppose.


>  > If none of this helps at all, then the problem is past the label and
>  > in to the filesystem structure itself.   Then I think you are stuck with 
>  > tracing superblocks as I pointed out before.   That is going to take some 
>  > study but it might work.
> Yep, it depends on how precious this data is, but no learning is wasted.
> Cheers, Ian
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