dd hung up by disk errors

[Ross Boylan <ross@biostat.ucsf.edu>]

I have a bad drive in a laptop and am attempting to salvage what I can
with (roughly)
dd conv=noerror,sync if=/dev/sda3 of=/nfs/backup
where the of is NFS mounted from another system.

This keeps trying when it encounters a disk read error, but there are
lots of errors and it is very slow (only 200MB transferred in c 9
hours).  The first 62G went OK, but the disk is c 75G.

I'm willing to accept some sectors as lost, but it would really help if
there were a way to do so quickly.  Is there?

I think the drive is SATA; it's in a Dell Latitude D630 laptop.  I
booted off a Knoppix 5.1 CD. sda3 is an NTFS partition.

Thanks.
Ross Boylan