http://www.forensicswiki.org/wiki/Ddrescue

http://www.gnu.org/s/ddrescue/ddrescue.html

http://www.garloff.de/kurt/linux/ddrescue/

The increased use of virtualization has made common the situation where you have layers of drives, partitions, RAID, logical volumes then more partitions, RAID and LVs on top of the first layers.

Central to recovering data is the use of kpartx to find and activate the additional partitions.

Primary link: http://blog.normation.com/2011/04/07/mounting-partitions-stored-in-a-logical-volume-or-a-disk-image/

http://pve.proxmox.com/wiki/SMEServer_LVM_Recovery_using_Knoppix_LiveCD

http://www.linuxjournal.com/article/8874

http://www.debianadmin.com/recover-data-from-a-dead-hard-drive-using-ddrescue.html

http://www.cgsecurity.org/wiki/TestDisk

http://www.howtoforge.com/data_recovery_with_testdisk