WHDD is a HDD diagnostic and data recovery tool for Linux.
It is capable of testing a hard drive with reading and writing, providing intuitive visualization of the process. Visualization or these tests is very similar to MHDD.
Amongst others, there is a function for copying the device. The copying procedure algorithms are optimized for least harm to already-defective source device. The meaning of this becomes clear in a demo:
(Forum engine did not allow me to post a link, so you may search it manually on YouTube - "WHDD scanning and smart copying of defective HDD".)
WHDD may work with your hard drives on low level, sending ATA commands to device, the benefits are:
  • no system freeze while accessing damaged device (device is soft-reset on timeout);
  • better timing precision.