In this scenario the disk drive /dev/sdb is about to fail and we want to create an exact copy on a new disk drive /dev/sdc, which should be at least the same size as the source drive.

First, copy every block without read error and log the errors to /root/rescue.log.

Warning

All data on /dev/sdc will be lost, including the partitions and partition table.

root #ddrescue -f -n /dev/sdb /dev/sdc /root/rescue.log

Second, copy only the bad blocks and try 3 times to read from the source before giving up.

root #ddrescue -d -f -r3 /dev/sdb /dev/sdc /root/rescue.log

Now the new drive could be mounted and the file system checked for corruption.