http://hoshan.org/2011/09/a-brief-manual-on-how-to-use-ddrescue/
Extremely effective in recovering data from an ailing drive.
Used only for Linux.
ddrescue [options] infile outfile [logfile]
ddrescue -d -r3 /dev/hdc hdimage logfile
invoke program, set to 3 retries, location of drive, to image file name, then to log file name. As long as you keep a log file, drive can resume exactly where it left off during replication program. After done recovering (sometimes takes over 50 hours), the image can be restored to an alternate drive as long as it has more space, or the image can bemounted in linux after issuing fsck. http://partissci.blogspot.com/2009/01/how-to-repair-damaged-linux-partition.html