GNU ddrescue vs TestDisk

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.

TestDisk is free, open-source software for recovering lost partitions and helping disks boot again when faulty software or human error causes the problem. It can repair partition tables, recover deleted partitions, rebuild or restore FAT and NTFS boot sectors, fix FAT tables, and repair an MFT using its mirror. For file recovery, it can undelete files from FAT, exFAT, NTFS and ext2, or copy files from deleted FAT, exFAT, NTFS and ext2/ext3/ext4 partitions. Listed partition-recovery formats also include APFS, HFS+, XFS and ZFS. It works with hard drives, USB drives, memory cards, disk images, DAS, SAN and Linux RAID devices. The portable application is used by extracting its files; no installer is required. Listed operating systems include Windows, macOS, Linux, DOS, FreeBSD, NetBSD, OpenBSD and SunOS. TestDisk is licensed under GNU GPL v2 or later. The maker says it does not connect to the internet or send information about the user, computer or data. The download page lists version 7.2 dated February 22, 2024, and 7.3-WIP as beta.