GNU ddrescue vs R-Undelete

GNU ddrescue copies data from a file or block device to another location, prioritizing readable areas when read errors arise. Its basic recovery process is automatic, so it does not require stopping and restarting at every error. A mapfile records progress; an interrupted job can resume and reread only blocks that still need attention. The algorithm handles good areas first and defers bad or slow ones to reduce unnecessary drive movement. It works with kernel-supported devices, including ATA, SATA, SCSI, floppy disks, and flash media cards, and can use direct disc access where supported. Fill and generate modes provide additional ways to write selected output areas or create an approximate mapfile from an input and partial copy. The package includes ddrescuelog for manipulating and comparing mapfiles and checking rescue status. GNU ddrescue is free software under the GNU General Public License, version 2 or later, with no paid plans stated. POSIX systems are recommended; the manual discusses Cygwin but warns of potentially misleading permission errors. A device or partition used as the destination will have its data overwritten. Because ddrescue needs random access, create an uncompressed image before compressing it.

R-Undelete has no write-up on Specifiction yet; its figures are above.