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GNU ddrescue
What it is
GNU ddrescue copies data from a file or block device to another destination, attempting readable areas first when read errors occur. Its basic recovery process runs automatically, without requiring a restart after each error. A mapfile records progress so an interrupted job can resume and focus on blocks that still need attention. The algorithm handles good areas first and postpones bad or slow areas to reduce unnecessary drive movement. It supports kernel-recognized device types, including ATA, SATA, SCSI, floppy disks, and flash media cards; direct disc access is available where supported. Additional modes allow selective writing to output areas and creation of 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 and warns of potentially misleading permission errors. Selecting a device or partition as the destination overwrites its data. Because the tool needs random access, it cannot create a compressed image directly; create an uncompressed image first if compression is needed.
For and against
For
- Recovery runs automatically through read errors
- Mapfile lets interrupted jobs resume
- Prioritizes readable areas before bad or slow ones
- Includes ddrescuelog for mapfile tasks
- Free software under GNU GPL version 2 or later
Against
- Using a device or partition as destination overwrites its data
- POSIX systems are recommended
- Cannot create compressed images directly
The verdict
GNU ddrescue offers automatic copying with resumable progress and tools for working with mapfiles. Choose the destination carefully, and use an uncompressed image before compressing if needed.
Who it suits
GNU ddrescue suits users who need to copy data from files or devices while managing read errors and resumable recovery. It is aimed at users working on POSIX systems, though the manual also discusses Cygwin.
Plans and prices
GNU ddrescue
Free software under GNU GPL version 2 or later · no paid plans stated
Read 12 Oct 2026 · gnu.org
On the record
- Additional modes
- It includes fill mode for selectively writing output areas and generate mode for creating an approximate mapfile from an input and partial copy.gnu.org · read 12 Oct 2026
- Automatic recovery
- Its basic recovery operation is fully automatic and does not require stopping and restarting at each read error.gnu.org · read 12 Oct 2026
- Companion utility
- The package includes ddrescuelog, which manipulates mapfiles, converts formats, compares mapfiles and checks rescue status.lists.gnu.org · read 12 Oct 2026
- Compression limit
- Because ddrescue needs random access, it cannot create a compressed image directly; the manual advises creating an uncompressed image first and compressing it afterward.gnu.org · read 12 Oct 2026
- Data-loss risk
- Using a device or partition as the destination overwrites data stored there.gnu.org · read 12 Oct 2026
- Device compatibility
- The tool works with device types supported by the kernel, including ATA, SATA, SCSI, floppy disks and flash media cards.gnu.org · read 12 Oct 2026
- Direct access
- Where supported, ddrescue can use direct disc access to bypass the kernel cache.gnu.org · read 12 Oct 2026
- Integrations
- The GNU project links to ddrescueview for viewing mapfiles and ddrutility and Partclone for related recovery workflows.gnu.org · read 12 Oct 2026
- License
- GNU ddrescue is free software licensed under the GNU General Public License, version 2 or any later version.gnu.org · read 12 Oct 2026
- Memory card recovery
- Yesgnu.org · read 23 Sep 2026
- Operating systems
- POSIX systems recommended; Cygwin support is discussed in the manualgnu.org · read 23 Sep 2026
- Purpose
- GNU ddrescue copies data from a file or block device to another, trying to rescue readable parts first when read errors occur.gnu.org · read 12 Oct 2026
- Recovery algorithm
- The algorithm prioritizes good areas and schedules reads in bad or slow areas for later to reduce unnecessary drive movement.gnu.org · read 12 Oct 2026
- Resumable jobs
- A mapfile tracks rescue progress so an interrupted recovery can resume later and reread only needed blocks.gnu.org · read 12 Oct 2026
- Recovery sources
- Files,devices,partitions,optical media (CD-ROMs/DVDs),kernel-supported devices including ATA,SATA,SCSI,floppy disks,and flash media cards such as SDgnu.org · read 23 Sep 2026
- Support
- The project directs bug reports and discussion to the bug-ddrescue mailing list.gnu.org · read 12 Oct 2026
- Windows caveat
- The manual recommends a POSIX system and warns that Cygwin use may produce misleading permission errors.gnu.org · read 12 Oct 2026
