I've used dd to clone hard drives before using 'dd' and a live cd, but have run into a problem.

The issue:

dd fails with an "Input/Output Error" on /dev/sda3 , even though windows "check disk" (chkdsk) says it's ok.


  • Trying to replace my laptop hard drive w/ a faster one of the same size
  • Laptop has NTFS on a 320gb hard drive
  • Booting into knoppix
  • Knoppix recognizes 'original' drive(/dev/sda)
  • I am using a usb connection for ‘new' drive (irrelevant, but just an fyi)
  • Knoppix recognizes the usb drive as /dev/sdb
  • Using dd, as follows:

    dd if=/dev/sda of=/dev/sdb

  • `dd gives the I/O error above at 82Gb (out of 320Gb)

  • I then tried checking each partition as follows and found it failed on /dev/sda3:

    dd  if=/dev/sda1 of=/dev/null
    dd  if=/dev/sda2 of=/dev/null
    dd  if=/dev/sda3 of=/dev/null 
  • I have ran windows xp chkdsk on the offending drive in both "find only" and "find and fix" mode and it reports no errors


How can I find and fix the error on my original hard drive partition (i.e. /dev/sda3) so that dd reads it successfully?

3 Answers 3


Use ddrescue for that, it's able to read damaged disks.

And chkdsk probably won't find the issue because it only does basic checks of filesystem integrity; by default, it won't check all the partition space for read errors caused by damage.

  • 3
    The package for ddrescue is gddrescue on ubuntu if that's the livecd you're using. If you just do ddrescue you get dd_rescue which is a different older package.
    – Col
    Sep 4, 2009 at 8:16

I ran into the same problem and my OpenSUSE livecd didn't include ddrescue or Clonezilla. However, when I checked out the dd manual, I discovered that there was an option "conv=noerror" that allowed dd to continue past the I/O error.

dd conv=noerror if=/dev/sda of=/dev/sdc

To copy data to different HDD attempt use special tools. Norton Ghost (commercial) or Clonezilla (opensource) http://clonezilla.org/

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