ddrescue For Mac Publisher's description
from Antonio Diaz Diaz
GNU ddrescue is a data recovery tool.
It copies data from one file or block device (hard disc, cdrom, etc) to another, trying hard to rescue data in case of read errors.
The basic operation of ddrescue is fully automatic. That is, you don't have to wait for an error, stop the program, read the log, run it in reverse mode, etc.
If you use the logfile feature of ddrescue, the data is rescued very efficiently (only the needed blocks are read). Also you can interrupt the rescue at any time and resume it later at the same point.
Automatic merging of backups: If you have two or more damaged copies of a file, cdrom, etc, and run ddrescue on all of them, one at a time, with the same output file, you will probably obtain a complete and error-free file. This is so because the probability of having damaged areas at the same places on different input files is very low. Using the logfile, only the needed blocks are read from the second and successive copies.
Ddrescue recommends lzip for compression of backups, because of its reliability and data recovery capabilities.
Recordable CD and DVD media keep their data only for a finite time (typically for many years). After that time, data loss develops slowly with read errors growing from the outer media region towards the inside. Just make two (or more) copies of every important CD/DVD you burn so that you can later recover them with ddrescue.
The logfile is periodically saved to disc. So in case of a crash you can resume the rescue with little recopying.
Also, the same logfile can be used for multiple commands that copy different areas of the file, and for multiple recovery attempts over different subsets.
Ddrescue aligns its I/O buffer to the sector size so that it can be used to read from raw devices. For efficiency reasons, also aligns it to the memory page size if page size is a multiple of sector size.
What's New in This Release:Added new option `-I, --verify-input-size'.
В· Added new option `-x, --extend-outfile'.
В· main.cc: Verify that infile, outfile and logfile are all different.
В· Non-tried blocks are now read aligned to cluster-size sectors.
В· rescuebook.cc: Improved skip algorithm for the split pass.
В· ddrescuelog.cc: Set default block size to 512 same as ddrescue.
System Requirements:No special requirements.
Program Release Status: Minor Update
Program Install Support: Install and Uninstall