GNU ddrescue

What is GNU ddrescue?

GNU ddrescue is a powerful data recovery tool that enables users to copy data from one file or block device, such as a hard drive or CD-ROM, to another, even in the presence of read errors. The tool's basic operation is fully automatic, allowing users to initiate the recovery process without the need for constant monitoring or manual intervention One of the key features of GNU ddrescue is its efficient use of a logfile, which records the progress of the data recovery process. This logfile allows the tool to focus on only the necessary blocks, reducing the time and effort required to complete the recovery. Users can also interrupt the rescue at any time and resume it later from the same point, without losing the progress already made Another unique aspect of GNU ddrescue is its handling of bad sectors. Instead of writing zeros to the output when encountering bad sectors in the input, the tool preserves the existing data, ensuring that any recoverable information is not overwritten. Furthermore, the tool does not truncate the output file unless explicitly instructed to do so, allowing users to continue the recovery process on the same output file during subsequent runs The tool also offers an automatic merging feature, which can be particularly useful when dealing with multiple damaged copies of the same file or storage medium. By running ddrescue on each copy, one after the other, with the same output file, the tool can recover a complete and error-free version of the data, leveraging the low probability of having damaged areas at the same locations across different input files For users working with recordable CD and DVD media, ddrescue provides a valuable solution. These storage formats can experience data loss over time, with read errors gradually spreading from the outer regions towards the inner areas. By making multiple copies of important CDs and DVDs, users can later use ddrescue to recover the data, taking advantage of the tool's efficiency and ability to handle read errors Additionally, GNU ddrescue offers a "fill mode" feature, which allows users to selectively overwrite parts of the output file. This functionality can be used for a variety of purposes, such as wiping data, marking bad areas, or even, in some cases, repairing damaged sectors

Highlights

• Fully automatic data recovery process, no need for constant monitoring or manual intervention
• Efficient use of logfile to focus on only the necessary