Re: dd question

[Pádraig Brady]

Peter Stuczynski wrote:
> Hi,
>    
>   I'm new to linux and I have a 80Gig WD drive that's going bad. I purchased 
> another 80Gig WD drive and I'm using dd to try to transfer the information to 
> the new drive. I used:
>    
>   dd if=/dev/hda of=/dev/hdb conv=noerror
>    
>   It's been running for about 24 hours and now I am getting:
>    
>   dd: reading '/dev/hda': Input/output error
>   94665360+0 records in
>   94665360+0 records out
>    
>   will this eventually continue or will it continue to loop on this error.?

I think conv=noerror will not do what you want.
That will skip bad sectors, but on the destination disk
the bad sectors aren't accounted for at all, so all
sectors after the bad ones will be shifted down accordingly.
You want to specify conv=noerror,sync to write zeroed blocks
on the destination corresponding to the bad blocks on the source.

Also dd is going to be inefficient in this application
as its reading/writing 512 bytes at a time (synchronously).

Instead have a look at ddrescue:
http://www.gnu.org/software/ddrescue/ddrescue.html

Pádraig.