Dd clone hard drive: Input/Output Error though “chkdsk” says OK

cloneddntfs

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.

Context:

  • 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

Question

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

Best Answer

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.

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